They provide compression which can offer some assistance. Think about how it feels on your hips if you squat with a snug pair of jeans.
Anyway, it depends on your goals. If youre going to wear them tightly for assistance, then I wouldnt advise squatting beyond true parallel because that can stress the patella more.
As a safety tool, I dont really see them of high value. Theyre kinda like a belt in my opinion: if youre not doing the movement correctly then they are of actual use, otherwise no.
If youre squatting properly, progressing gradually, and making sure you have structural integrity in the tendons and balance between your quads and hams, then you shouldnt have a problem.
For some people, the pain in squatting occurs because they stop at 90 degrees of knee flexion rather than going all the way down. Again, it comes down to squatting properly.