Addressing the original post, I think it boils down to point number 2 (it feels bad to mess up a positional) and points 1 and 3—(people who main other rolws not liking how melee plays, and 'wall bosses')—grow out of point 2 as people try and justify why they think positinals should go.

And, like, I get it a little? I kick myself a bit when I miss a positional. But not too much, because more often than not, Its because I prioritized not getting murdered by the boss surprising me with a cleave, or getting caught in AOE spam.

Which brings me to a bit of an unkind observation: I'm not a top tier player by any stretch of the imagination, but I see plenty of people (tanks, DPS, etc) who just... kind of stink at the not dying part—even before you add positionals to the equation.

Do I think EVERYONE who thinks positionals should go are just bad at staying alive while playing 'optimally'? Not necessarily.

I DO think positinals make a good scapegoat for that particular problem though.

Removing them might make things easier, sure, but also... Not really? Because making jobs 'easier' or less busy won't help with having the sense to prioritize staying alive/doing mechs as their first priority, and hitting their buttons 'perfectly' as their second.