That model stops working as soon as you try to distribute software at scale. You need some kind of standardisation and baseline. Otherwise your customisations conflict with someone else's customisations, with consequences that vary from mildly annoying to catastrophic. And the whole idea of shared software collapses.

It would work if you had strict access control to each feature in a common code base. But Git hadn't been invented yet.

The other issue is performance. Compiled ST isn't particularly slow, but you lose the modifiability. Interpreted ST has a mixed profile - some features are slow, some are fast - but generally it was slow compared to C.

Today that doesn't matter so much, but it was a drawback at the time.

It's a seductive model and I totally get the appeal. But it's not quite as straightforwardly superior as it might appear to be.