I will start using htmx as soon as there is a 20K MRR startup built only with it.
My startup using htmx was there - and it was acquired successfully. They migrated pretty quick to react after the acquisition due to team dynamics (offshore big teams - seeped into JS heavy client, thin server culture). htmx was a struggle there as well. It worked amazing for us as a small team where everyone was full stack and I always build using htmx-first now. But, it is a struggle for folks who have been working…
One advantage of htmx (along with web components and standard html+css) is that migrating to anything else is much easier than the other way around. A rewrite from an htmx app to a React app can be trivial. A rewrite from React to anything else will not be.