idk if nesting is the reason people used tailwind. imo it's more that css itself is a lot of complexity and overhead to write if you already have nesting and reuse in whatever you're using to produce html, ex react. I'd rather not have to maintain a css tree and a component tree when it can all be colocated.
Tailwind is the epitome of someone trying to make one tool that does everything then tries to sell you on buying only that one tool. As the old saying goes: When all you have is a hammer, everything looks like a nail. Sure you can hammer a screw into a wall, but if you used the right tool for the job to begin with, you could also unscrew the screw and replace it later without needing to fill the old hole or make another hole in the wall.
Tailwind exists purely because developers keep trying to learn CSS the wrong way from people who don't know how to use it, then get frustrated when it doesn't work out.
The problem is that when you're starting out, you don't know the difference between good and bad teachers.