Not because they aren’t excellent, but because they aren’t great to work with. C# and .Net has never been greater than they are now, and yet we increased our productivity by switching to Node/Typescript by around 20%, with the added benefit of having a single language across the stack. The latter was the primary reason for the switch and the increase in productivity came as a sort of surprise and we’re honestly still trying to figure out why our developers produce things which are measurably better at a faster pace with TS and for many a change of tech from something they’ve used for many years. I see some similar reflections and stories coming from the lunar team on why they switched from Java to Go.
That being said. Whatever works is always the best technology. If that’s C, C#, PHP or whatever, then that’s always going to be your best answer. I don’t think there is really any reason to “pick” the right technology from the get go, you can always worry about that when/if it becomes a problem. We didn’t switch to TS from C# because we disliked it, we did it to share our resources better. Eventually if/when we grow enough, we’re likely going to have to change things. Though maybe not. Lego seems to be doing fine on mainly Node and I doubt will reach their size any time soon.