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

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.