Update: ffs I'm not defending hr, they're usually incompetent buffoons. But they're the incompetent buffoons you need to get past if you want to get hired. And I don't know about you, but when Frito Pendejo said "I like money" I kinda agreed with him. Anyway back to my OC:
Why? They're HR and hiring managers, not IT specialists.
Try seeing it from HR's perspective. They post a job and get +200 applications. The success criteria is not hiring the best candidate, it's hiring a suitable candidate. Given that premise, why would you read through all 200 applications, when there's someone with a nice website and cool sounding software, who promise that their product can sort through the resumes and only pick the relevant ones for you?
Heck, I'm definitely going to be looking for an ATS testing site for my CV now. It really doesn't matter what we think of it. If you want to communicate you'll have to do it in a way that your recipient will understand, and if my recipient is a PoS software that can't read PDFs, then writing my CV in latex is probably not the most effective way to communicate.
Tbf I've done that with first joblistings. Like "ask questions that a suitable candidate for the following joblisting should answer in a job application". And then pasting my cover letters asking for relevancy and phrasing help. Maybe I should try for ATS optimization.