The learning curve certainly is a lot steeper than Photoshop or similar tools, and the GUI is very much counter intuitive compared to other graphics tools. Add that it lacked tons of nondestructive editing, smart objects etc. The poping out of different panels also get annoying super quick.
Because it is about learning. You can't learn a hard phrase on an instrument without slowing down. You can't touch type fastly without learning the motions slowly first.
The more I know, the more I realize how much I don't know... you make a fair point. Challenges definitely evolve throughout a career. Lately, mine have shifted towards C-level decisions and their life-altering consequences. Discussing these "struggles" with those who've navigated this path could be extremely valuable.