True enough, by the way. I don’t know whether I should laugh at or feel sorry for those instant-gratification kiddos who first spend thousands of real-world ‘coins’ 
to max everything ASAP (‘I Wanna Play NOW!’), then quit, because they are disappointed. 
I beg to differ. I’ve maxed all my Mercs (completely F2P, by the way), moreover, I’ve finally quit PvP, which has been less and less fun while more and more stressful or frustrating, however, this might be one of the best times I’ve been having with Mercs, partially due to those fun visitor tasks (I’ve got some more interesting or challenging ones, too), which, despite their randomness, can be almost like puzzles from those events, partially because now I can play or try whatever I want, no need to optimise or farm anything while at it.
REACHING LEVEL 30 (LEEROY JENKINS!!!) has never been a particular problem, by the way, and training grounds are more of a convenience feature, although I personally aprreciate it a lot. Besides… Are you in a hurry? Do you want to speed-run the whole mode, then start producing angry posts or videos how you are FRUSTRATED and BURNT-OUT with the mode?
Which is not quite true, at least re high-level dungeons (PvP is just, as said, not fun in general, in my opinion) — moreover, nowadays many more of them are solvable ‘on a budget’, e.g. with only rare mercs in the party (which itself is a puzzle, by the way, which one could enjoy), since we’ve received a number of phenomenal ones.
Which is generally not even necessary for PvE, by the way.
Yeah, there’s still some grinding with doing task chains etc, admittedly, but it’s not as bad as you describe.
I’d say it is the most enjoyable mode for me.
Exactly.
Funny, because people bemoaning this might have spent much more grinding their ladder or BGs.
I always say that there’s absolutely no hurry with this mode, it’s not about INSTANT GRATIFICATION and getting everything RIGHT NOW, then toying with it for a little while and becoming FRUSTRATED (as with practically anything in this era of cultivated ADHD, overconsumption and getting oneself ‘amused to death’, as the classic put it) — instead, I’d recommend playing at your own pace, enjoying the road (or just relaxing if you’re doing a little farming — that’s an option, too) and the different stages of this journey — I’d say they are fun in their own various ways, then seeing where you get with it.
(Updated, some edits made)