I still see this thing of expertise being overvalued in many organizations, and it's completely toxic. I find it's more common and successful private companies, but it can happen at public companies too.
Typically, you get people that joined 10+ years ago, they implemented certain key systems / features when the company was small, nimble, and not too many actual customers to deal with. They probably worked long and hard to make that happen, probably largely without interfere Then, the company / product is successful, they promoted, have a kids, and end up being a full-time "expert" who writes emails and has opinions on present-day implementation details and changes, but is nowhere to be found when it comes to actually implementing anything or dealing with practical, day-to-day problems.
Meanwhile, the more junior, recent joiners who are doing all those things get no say in the direction of what they're working on, and eventually leave to be replaced by the next batch of new joiners.
I was that expert recently, but in a university lab, with undergrads as my juniors... I spent 90% of my time trying to convince people NOT to rip out everything and start from scratch; not to depend directly on database details, not to shove everything into mongodb and react, not to implement a new full stack for every subsection of the project they were working on.
One guy was supposed to have modify an android app to update repeatedly every 5s for a simple, one-user management view; started it by setting up a firebase instance
Another decided that rdbms was no good, and spent the entire semester trying to convince me to switch to mongodb, because "mysql can't handle the number of requests we're making" (~50/day, maybe ~1k/day long into the future).
A third guy decided the message queue was a bottleneck, and came to me with a proposal to reimplement it; after about 15 minutes, I finally pulled out from him that it would take an expected 6 weeks to implement, and EVERYONE had to stop working in the meantime. Simply looking at the logs, the message queue was clearly not a bottleneck, and there was no reason it couldn't be worked on while the current one stays useful...
My primary job was just keeping the project from burning down, let alone improved. And every one of those students thought I was holding the project back, as I desperately tried to maintain a working system.
That might have just been the inexperience of undergrads, but I have some sympathy for your "experts". Everyone's just gobbling up the marketing, confidently pushing ideas derived from inexperience and no one has any respect for history (at least, in my uni). I was also only one year split from the project, and it had changed from 2 developers to 20, so not the same scale as you're suggesting
It can't be overstated how important it is for more senior level members of a team to be aware of this happening. Very often a junior has "great" ideas, but they are based on very little factual data. They are not yet able to see the whole picture, and it is the job of seniors/managers etc. on the team to guide them.
Careful, though. I've seen many "more junior, recent joiners" want to do some pretty risky things with little upside.
Ideally, this is no different than being a parent. You want to help your kids not make mistakes. Thing is, they are the ones taking on the risks, you are not. Offer advice and work with them, but ultimately, you will have to let some of them make mistakes. If you are lucky (and many folks will be), some of the mistakes will turn out as hugely successful gambits. :)
"has opinions on present-day implementation details and changes, but is nowhere to be found when it comes to actually implementing anything or dealing with practical, day-to-day problems."
I see that a lot in my company. These guys basically have stopped learning and give advice based on what they did years ago. Only a selected few keep evolving.
In some areas I am at risk to also become the resident expert. I wish I could just hand it off to someone else but what do you do yourself then?
You tell your boss(es) about your concerns and onboard some new people, and you do something new. Either within the company; find a team that needs people or try to pioneer a new app, or change companies. Or accept being the expert and enjoy a promotion!
I've worked at a few places of vastly different sizes. From a company with only three devs, an office with three hundred devs, and a fortune 500 with over 3000 devs (not necessarily in that order). Maybe I've just been lucky, but at all of those places I've had conversations with my managers along the lines of "team x is doing something I find interesting and eventually I would like to do that, can you help me get there?" or "I have an idea for a project x that would be useful to us, can I block some hours to work on that?". Generally they have been amenable, and if not then I've moved companies. You need to be responsible for your own career, and I like working at places that encourage personal development :)
This used to work for me until around senior level but after moving up a little more (with corresponding salary) I find it harder to move around while keeping the salary.
I don’t know if it’s toxic so much as business as usual in any mature company. A lot of mature SV companies want to be different on this front but they just fundamentally aren’t.
I see it as the default, unless there's a strategy to do something about it.
I firmly believe any company needs to be pruning their employees on an ongoing basis - think Jack Welch's bottom 10%, or investment bank annual tidying before bonus season.
That doesn't mean employers need to be nasty about it, I think you can thank these people for their service, give them a nice severance package, a good reference letter, but you don't need to keep employing them until they reach senility and retire.
Typically, you get people that joined 10+ years ago, they implemented certain key systems / features when the company was small, nimble, and not too many actual customers to deal with. They probably worked long and hard to make that happen, probably largely without interfere Then, the company / product is successful, they promoted, have a kids, and end up being a full-time "expert" who writes emails and has opinions on present-day implementation details and changes, but is nowhere to be found when it comes to actually implementing anything or dealing with practical, day-to-day problems.
Meanwhile, the more junior, recent joiners who are doing all those things get no say in the direction of what they're working on, and eventually leave to be replaced by the next batch of new joiners.