They are only delayed from joining parties they are not yet ready for. Whether this comes in the form of users demanding certain parse numbers, a Faust-esque equivalent or something else is irrelevant. If you aren't able to overcome this obstacle, you aren't ready. Removing said obstacle doesn't magically make those players able to approach the content. They're simply joining groups who will be none to happy by their poor performance. Regardless, this hypothetically serves no purpose to a parse discussion since parses don't really act as a "gatekeeper".
You know what gets really old? When I clearly label my PF "farm" and get someone who has utterly no idea what half the mechanics are, dies repeatedly and/or does comparable damage to a tank. The proper response is to not be an inconsiderate jerk. Why is it okay for you to join farm parties when you aren't capable of performing a decent rotation. We're not talking about a mistake here or there. Those happen to the best of us. We're taking about people who show little to no desire to improve yet expect everyone else to do the work. What do I lose? My time. Dog farms necessitate no less than 99 runs; more if you don't want to wait six months. Even if a minute is added because of consistent mistakes from one or two people, that means an extra Suzaku every 8-10 clears. In the end, I'll have added anywhere from ten to fifteen more runs, assuming I don't get a lucky roll all because someone couldn't be bothered to put in the effort to improve themselves before joining. I find hilariously ironic you accuse people unwilling to carry as being selfish yet don't apply that logic to the person expecting everyone else to compensate for their own laziness. Who's actually lazy in a scenario where the Warrior is out-DPSing a Samurai despite both having roughly equivalent ilvls?
Putting that aside, if I wanted to teach you how to do the fight, I would be in a learning party. The whole reason we have such a distinction is because people have already progressed beyond a certain point and want to progress further, not spending another hour or however longer teaching someone else. In the case of a farm party, you should know the whole fight. That is what farm parties are; farming the content. Not teaching someone mechanics they should already know. Do some people overreact in a learning party? Sure, but you're being deliberately hyperbolic like usually. I purposely used a farm party per my example, thus this shouldn't be your first time.
And? Some people are jerks. Welcome to life. A parse or "gatekeeper" isn't going to change that evident by the fact despite parsing technically being against the tos, people are still jerks. Therefore, the parse isn't impacting it. People with a shitty attitude will have one regardless. And people who are otherwise decent won't magically become jerks if ACT were suddenly allowed.