I don't care what Bunny Brunnel says...unless he's going to come play my bass. And it isn't just aesthetics - playing music is a psychological game and technology, tuners, and the like are very poor at explaining how that all works together.
I can only offer my personal experience. I have a tougher time playing "well" with fretlines. My theory is that the lines shift the balance toward visual over aural in my little brain, and that is enough to throw me off. I have owned both, and my first fretless was a defret where I could see the lines. I also have played upright over the years so that may influence it to. Yes, I use the dots as a reference point - but they are just that, a reference. One problem (again, my theory) is that a player with fretted experience will unconsciously accept the fretlines as an absolute rather than a reference. And with frets parallax is mostly a non-issue. So then that needs to be overcome with practice.
I agree that there is no "cheating" and no right or wrong. But I will still maintain that for some players fretlines make things harder, not easier. Just depends on how you're wired, what your background is, etc. What gets annoying to some are sweeping generalizations ("fretlines are cheating" or "unlined players are snobs"). Too many people have too many chips on their shoulders. And the way to fix that is practice imho...that would be my sweeping generalization. Practice can solve most anything. And if it can't, then maybe you're not "university material" (to quote Nigel Tufnel). Not everyone can play music at an extremely high level...just like not everyone can play sports as a pro, etc. No shame in that, but good to have a little realistic perspective.