I basically was squarely the target group of bootstrap, and used it for lots of projects in all versions. I didn't actually care much about their technical progess (float, flex, css-grid, whatever), I just copypaste from the available widgets and add in my data.
Just LAST WEEK I learned that my favorite web framework (https://phoenixframework.org/) now ships with Tailwind preconfigured by default. I also heard good things about it from trusted colleagues. So, for the next big project I decided to jump in. Still I kind of have concerns: I need "typical components" like cards/tables/grid/... to be only a copypaste away; and I need to allow some designers be able to tweak the overall look and feel, roughly like a theming file where fonts/colors/... are defined at a single place. I hope it will be smooth after all these years of bootstrap and the "muscle memory" of how to compose pages with it.