Also, Bootstrap gives you plenty of copy-and-paste ready examples, including accessibility enhancements. Accessibility can be an after-thought to not just devs, but many designers, but Bootstrap helps put it right up front for the lazy developer.

Anecdotally, I've sometimes seen better quality websites for a lot of the little "polish" things like accessibility (which isn't really "polish", is it?) from the laziest "just use Bootstrap" developers than from the most hardworking Tailwind developer+designer combos.