On the one hand, I completely agree that parsers are an important if not necessary tool for savage raiding. But I see two problems with introducing them into the game.
1) The trickle down. Everything that's done in end game trickles down to the rest of the game, through EX trials, 24 mans, and all the way down to basic leveling dungeons, even when it's absolutely unnecessary. It happened with tanks *have* to wear all str accessories, it happens with tanks should *never* use their tank stance, leading to tanks in sub 50 leveling dungeons never using it and mobs going everywhere, because that's what everyone says the way to play is.
2) Percentages. Say only 5% of people using a parser will ever be a dick to someone about it. 5% of players who currently know where/how to get and setup parsers and know how to use and read them and are willing to go outside of the game to get them, despite it being technically a tos violation, is a much much smaller amount than 5% of every single player in ffxiv. More people using it, more chance of running into one of those dicks.
Now I'm not worried that the current people who parsers will be dicks about it. The people who use it now are likely for the most part to be players who do end game content and know how to properly read a parser, what all the different information means, how to analyze it and use it to improve their, and their static's performance. It's the random tom, dick or harry player that only see's parser = dps, bigger number = better and has no idea any of the nuances of it, or where it should be applied (see point 1). And if you think I'm underestimating the playerbase's ability to use parsers properly, what about the complaints about players that cant seem to figure out that some abilities should be used in order(combo)?
If parsers are right there, in game, available to everyone, they will be used in all content, all the way down to sastasha. People will assume SE put them in, so they have to be important and focus on them. People will use them, and they will judge others, and how they respond beyond that depends on the person, but I don't see a rosy future.
I do agree that there are some players who currently either can't(ps4) or won't(tos violation) use parsers but would like to have them for their own personal growth or the content they do. But, I think that's a waaaay smaller group of players than those who simply have no need to use a parser. And yes, it sucks for them, but I think keeping parsers out of game, and silently allowing 3rd party ones, is far better for the game and playerbase. I am absolutely for raiders to use the outside tool, and would be against any crackdown against it, but I don't think it belongs built into ff14.