As a living testament salient to the topic of this thread, I myself was advised to play really, really difficult songs for my level (4-5*) despite being a beginner. My friends all assured me that pushing myself very hard on these incredibly difficult songs would unlock the inner cokezero inside of me, so I ended up playing 4-5* for an entire month on no fail.
Did I progress? Not really. I improved at reading ar 9 a bit and I was able to move my hands pretty fast and mash fast as well, but I had very little aim or accuracy to speak of, and my technique and rhythm perception were horrendously lacking. I think I played this way until I was around 80-70k, after which I realized that my friends were all retards and I started all over and began relearning the basics from the bottom up.
Now I can actually play those songs that I mindlessly flailed on, but it took a logical approach. Sometimes effort alone isn't enough to carry you in everything. I once heard an analogy where there's a fly trying to escape outside of a house through a glass window. The fly keeps banging his head and charging into the window in the hopes that he may be able to escape outside, but no matter how many times he attempts this he will never make it out this way as the window is shut tight. As that analogy might illustrate, you shouldn't just play more and struggle needlessly, instead play efficiently and struggle in a smart manner.