Using the same language is useful for avoiding duplicated code, personally I find these being duplicated often:
* Form validation/data sanitisation code
* Translation/internationalisation
* Data (de)serialisation
Also you can do fancy things like server-side rendering, although Google is capable of searching SPAs now. I don't know much about SEO.
The argument for less code sharing is that if you are working with a lot of teams and service-based architectures, there are some merits to duplicate your code and keep them redundant, to 1) enable hiring from more diverse backgrounds and 2) reduce communication/maintenance friction needed when you make changes to components would otherwise be shared.
You make a good point- there's really only a handful of things that get duplicated. Maybe instead we should be working on just fixing up those things. Like if there was an easy way to share validation logic from the backend to the frontend... then that would only be needed to be updated once.
* Form validation/data sanitisation code
* Translation/internationalisation
* Data (de)serialisation
Also you can do fancy things like server-side rendering, although Google is capable of searching SPAs now. I don't know much about SEO.
The argument for less code sharing is that if you are working with a lot of teams and service-based architectures, there are some merits to duplicate your code and keep them redundant, to 1) enable hiring from more diverse backgrounds and 2) reduce communication/maintenance friction needed when you make changes to components would otherwise be shared.