It's interesting, because a few years ago I would have put this strictly under the "not invented here" fallacy, where we'd now be stuck maintaining another project for the foreseeable future. I used to press pretty hard to avoid it.
Now I wonder if the maintenance cost for this type of internal system has gone down to a level where that is no longer an issue.
I can see it going both ways. If knowledge work continues to roughly look the way it looks then I think maintenance is going to be an issue. Both in terms of keeping the spaghetti together but also in terms of all the bad design decisions you get from everyone bolting on their ideas. If however knowledge work becomes just talking to LLMs and occasionally interacting with an on the fly generated UI then maintenance becomes a non issue