Often books are a good source of distilled information and I think that’s why people pay for PE sites as well, so that they don’t have to do any critical thinking themselves.
The problem with PE is that it’s not a field where proper research has been done and things have been learned incontrovertibly to be true and these things can be distilled down to a pithy primer on the subject. It’s rather the opposite: the truth is boring and mundane, documented by individuals and when enough individuals say the same thing it forms some kind of consensus on what works. So what happens with the books and the pay sites is they have to present secret sauce, a special method that’s better than everyone else’s but strangely no one else is talking about or has tested over time. So, if you take that option, you are likely to get a skewed picture of what works, rather than better information.
There might be a time when good paid educational resources are available but it’s not now and there are good reasons to assume that these kinds of resources can’t exist yet because the basic work that makes these kinds of things possible hasn’t been done.