That's cool and all, but we're talking about a hypothetical world where they did implement the parser and you're opting out of it by disabling it for yourself. I feel like that's pointless if the parser already exists, you're just denying yourself information.
e: Also I don't really buy that optimal openers only exist because of parsers, it doesn't take a mathematician to do the maths necessary to work out what's a gain or loss based on potency alone. Parsers help you get a concrete number to prove your work (though simply just showing the maths you did would work just as well), but they're not necessary for actually figuring out your opener.
A parser (in terms of one that just displays damage dealt, crit rate, misses, etc) is basically useful for one thing: Knowing how much damage you're doing overall and at certain phases of the fight (and how much you're critting + missing). I think a better argument that puts parsers in a better light is that we wouldn't know the accuracy cap for any of the raids without having a parser. You could sift your way through the entire combat log or stare endlessly at your floating damage to see if you missed, but it's far easier to just have the parser track it.
There's two reasons I believe people are against parsers:
1.) They're afraid they'll get called out for not pulling their weight.
2.) They feel like they'll be unjustly called out for not pulling their weight when they've needed to sacrifice DPS to handle mechanics or their gear simply isn't high enough ilvl to pull the numbers others are expecting of them.
Both of these already exist, people just don't say "you're pulling low numbers, bye". They either kick you or just say that they think you're underperforming. There's also the helpful instances that people often overlook (because it's easier to paint with big broad strokes) of people who actually can see you're pulling low numbers and help you. This doesn't even include people who can see that they're pulling low numbers and excuse themselves or ask others for advice on how to get better.
Parsers give valuable information in a game where DPS checks exist and the end goal is to make the boss' HP reach zero. The amount of useful information gained from adding a parser far outweighs the microscopic amount of toxicity that would get introduced from the fraction of a fraction of players on PS4 (no toxicity would be gained from PC players as they already have parsers). It's, frankly, insane to me that people are still arguing against parsers in 2017 when PC players have had them since the game launched.