Some people think (my teacher is one of them) that it's not possible EVER to play really hard stuff unless you learn solid technique. One might be able to hack through the notes somehow, but it won't sound good. Learning such solid technique without a teacher and starting only with the hard stuff doesn't seem that likely. For a beginner something simpler is often very hard anyway, so it's all relative.
And "technique" required to play complex music is not only what you do with your hands, it's understanding the elements of the music and that sort of maturity takes time to develope as well. Then one either has to have excellent reading skills or memorizing skills to play large scale works. A beginner don't usually have those either.
OTOH to learn new things one has to be challenged, so I see little value in spending months or years with things that seem easy to learn. I do believe in "no pain, no gain", but the pain should be in your mind, not your body

My experiences in tackling things way too difficult: Usually had to give up at some point because it just didn't get better. But have found it rewarding to return to them later. So there's value in it if one knows when to stop, understands what the final product should be like, how far it is and accepts that some things may take a long time, like years instead of months.