rzmmm parent
Newer CSS features like flexbox, grid and media queries were added to reduce the need for frameworks like bootstrap.
Yes and no. The key selling point of Bootstrap (and similar) was that a design-blind (so to speak) backend dev/eng could use it and would have to work very hard to "design" something that was ugly, hard to look at, hard to use, etc.
Sure there are a bunch of helper classes, and such, but the key is an end product that does look like a backend dev/eng built it.
Frameworks still do a lot of the grunt work for the responsive breakpoints.