I think the point is getting an interview at companies that would otherwise completely ignore you if you applied through the normal process. Probably most valuable for people who do well on the tests but don't have a particularly impressive looking resume/CV.
I went through Triplebyte personally a few years back - twice. I was able to pass their evaluation/interview without any prep and got in to the matching phase.
The first time: I got matched with one company which ended up hiring someone before I could interview and another company that declined to go further after a phone screen.
The second time: I wasn't matched with anything.
The only reason I ended up trying to go through them was because I had a virtually nonexistent response rate through the normal application process while looking for my first job and I thought it would help me get through the initial resume filtering stage which is where I assume I get dropped all the time.
