You have a point, but there are cases where designers are doing something like styling CMS output and either don't have the skills or the possibility of doing s

You have a point, but there are cases where designers are doing something like styling CMS output and either don't have the skills or the possibility of doing something like adding classes conditionally to its output. Or perhaps asking a developer something like "Hey, can you add a class to X whenever it contains Y?" involves filing a ticket and waiting patiently for stakeholders to decide if and when it's necessary enough to devote developer resources to. And at any rate, removing classes and IDs as much as possible and just having a page full of semantic tags is generally a goal for a certain school of web development.