No it's pretty much correct. If you are confident in your own ability, you don't care about a parser or are already running one. And for those who want to get better, or aren't aware of how well they do? Parser can inspire to get better.

The ones vehemently opposed are the ones who do not want others to know how bad they are and have no desire for self-improvement.

The player base in FFXIV is pretty bad in general, so while a parser would certainly work on increasing average skill level, there would also be lost subs of crybabies who are angry that they are being kicked for being bad, then instead of getting better they just quit. It isn't hard to play at an adequate level, but it does involve practice and hitting a training target to become comfortable with a rotation.