That said, I know what you mean, and that's the point of something like Bootstrap Studio. You don't markup, it does. So now the "web designer" (perhaps in conjunction with some who actually understands basic frontend) is building a live "pixel perfect" mock-up.

Photoshop is a proxy. A Photoshop pixel isn't a web pixel. It's like saying, "I'm going to give you a rubber doll. I want you to build an exact replica that's human." Really?

People who still say "pixel perfect" just sound silly. "Web designer" with no sense for the difference between a hammer and a shovel aren't real web designers. Especially when far better tools are available, if you're willing to move forward.