And in my experience, these are _dangerous_. People go into "while we're at it..." mode, and it quickly turns into a big 2.0 kind of thing that takes forever.
I would argue that LLMs can speed this kind of thing up, but not by an order of magnitude or anything, just a bit. Unless there's high risk appetite.
Building products that no one really knows the internals of is crazy to me, and the methods people have of trying to mitigate that problem seem half assed at best
We have some and sometimes marketing comes back with some extra revenue from a partner if we build out feature X Y or Z for their new product launch. The contracts are signed so engineering has to do it or we’re blamed for lost revenue.
A few of those a year and you eventually end up in a similar situation.
If I didn't work on such a team, I would last exactly as long as it took me to find such a team.
With that said, I’ve also recently done a rewrite in a completely different sense, taking what used to be a web app and rebuilding from the ground up as a desktop app instead. Having the original code base for core concept reference, but rethinking the whole UI more than a decade on was IMHO a much better approach in that case.
The big problem with doing it this way is you end up with something structurally the same as what you started with, but potentially more code if you e.g. end up carrying your own reimplementation of Web Forms.