I've been using a much older version of photoshop for almost 9 years now. Photoshop Element 6, it's incredibly less complicated than the newer versions, but I can't do everything. I have found when you use photoshop so long you learn how to set it up to your preferences and liking. It's just a pain learning where everything is, but if I don't know I google.
However, I think its like that with any software. For me, who is used to Photoshop, if I go to a new software I get so confused, it may be the same for others going from one software to photoshop. All softwares take time to get used to and with how complex many of them are now, you may never learn how to absolutly do everything its capable of, but at the same time you may not need to. I've used to same software for years and still continue to learn how to do new things with it....and still have to goole how to do something if I don't know how.
In fact I have Medibang on my tablet, I've fiddle with it a little, but I find it confusing because its new to me, it just all a matter of learning I guess.