fwiw i've never experienced the drawback of separate languages for server and client. nor did i ever experience the benefit of single language across server and client.

being forced to use javascript on the server sounds like a cruel joke vs a benefit. I mean just simply from "i can literally pick anything for my controlled server env" vs "no we're a js shop cuz web"

edit to add: is it one repo? or maybe shared types. typescript is probably the strongest argument. can enforce integrity truly across the stack. but i don't think that's worth being forced into js environment and packages. community is forced to reimplement everything in js. no good.

HTML templates and the shadow DOM solved the only problem of separated languages that I have ever actually seen.

So yeah, once there was a benefit for using the same language. IMO, it never was worth the cost. But it doesn't exist anymore anyway.