The downside of yet another anything is that unless it is an order of magnitude better than what already exists is that it will split the available human resources. Not only that, it also isolates the users to within their own language/framework, promoting a monoculture (now there's a pun that could be made here).
While it's better than other in-house alternatives, it's not better for the entire ecosystem as a whole. The need for hyperlocal reverse proxies is a problem on its own, generally only solved this way due to organisational dysfunction or a very niche requirement.
Maybe? Turns out nginx, traefik and others came out after nginx and have gained some mindshare. Of course YARP has the "Microsoft" problem but I think the programmability is actually huge non-niche benefit (at least in what we've seen in practice)
While it's better than other in-house alternatives, it's not better for the entire ecosystem as a whole. The need for hyperlocal reverse proxies is a problem on its own, generally only solved this way due to organisational dysfunction or a very niche requirement.