Also, this came up today in a Youtube video - https://www.jetbrains.com/mps/

This has been referenced here a few times. I think we also had a discussion about it once, but it's lost behind the ancient fog. What was the YouTube video?

It was an ad before a video actually! I did not know that is has been discussed here before.

Oh weird, haha. Yeah, it seems like the sort of project that should appeal to this community in particular, but for some reason.. doesn't. Perhaps folks here have, like me, an excessive predisposition to Not Invented Here.

hahaha. That can be a good reason. I agree. I did not dig deep in it, I have to admit

The ideas behind it appeal to a good handful of us, just not the specific tool (MPS). I think it's ironic that it's supposed to enable one to mold the most direct or easiest model / language for whatever is being made, but provides a very locked down and cumbersome way of doing so. If MPS was bootstrapped in itself, then you could use MPS to change MPS. But then it wouldn't be MPS anymore; it would be the thing you are making with it (plus infrastructure you used to do it), and I don't think that's marketable as a product.