A problem this subforum has is that, if you look at a random assortment of the threads here, most of them will be started by people with very few posts. Most under 50, many under 10. Beta reading for someone is no small task, and it can be thankless if done wrong. You the reader are vowing to put hours of time into a novel to pick it apart and help the writer put it back together. How are they going to react? Will they say thank you, then put your advice to use? Or will they complain publicly about how their beta reader doesn't understand their genius and wasted their (the writer's) time? Or will they disappear entirely, without a single "thank you" for your effort? Many of us here have been burned by beta readers we barely knew (#3 happened to me), and many people who ask for beta readers here disappear after those first few posts. So many threads here get ignored, at least by people who have been around for a while, because we know what goes wrong when you try to help someone who hasn't shown they're willing to stick out through the tough stuff.
The ones by people who have been around and posting regularly tend to be responded to in PMs, I think.