I've personally found the opposite. In order to advance you need to know the specific techniques or mathematics and there are no hints or information on how to approach the problem. So it boils down to how much of that mathematics you know. If you don't then the brute force approaches take a long time to find the solution.
Often the techniques that you need for a harder problem, are discussed in a forum for an easier problem. Even more often the techniques that you need for a given problem are possible to work out from scratch. And the more you work out, the easier they get.
This can be very frustrating for people who are used to being spoon fed techniques, then given problems which use what they have just been taught. But it is a lot of fun for people who enjoy puzzles. If it isn't your cup of tea, that's fine. But don't dismiss it for people who enjoy it.
Disclaimer. I haven't personally engaged in the last few years, but I've spent a lot of time on it. I solved 598 and contributed a couple of puzzles as well. One of which they immediately saw a way to do that I hadn't, and put it out there with a difficulty level that I didn't know how to do! That was https://projecteuler.net/problem=240.
Wait, the math is discussed only in the forums? I thought one is supposed to gain mathematical insight from solving alone. As far as I have read here, forums are only accessible when having an account, which I don't. That would mean to solve later puzzles, I would need an account most likely.
The math is not only discussed in the forums. But yes, access to the forums is useful. You get to see not just how you solved the problem, but how others saw and tackled it. And often you'll learn something.
