How is it an illusion of saving time when you can one shot something like t5 in a good farm group, but possibly never beat it if you have 1-2 new players in the party?
Did you ever think the reason it takes you months to pass new content with learning parties is because they're new? Doesn't that make you at least somewhat understand why people put specific requirements into their party finder groups?
As far as you sneaking into t2 enrage; this is by far the easiest 'end game' fight in the game. There's no hard dps check, and I'm sure if you were up front about not knowing this fight most people wouldn't care. The only thing I strongly disagree with is the fact that you're going into party finder groups that specifically request people with set requirements, and you're wasting their time because you want to play with experienced people. When people blatantly ignore party finder requirements and waste everybody's time, I don't blame others for kicking and blacklisting them. I don't know about Balmung, but for every single fight from t4-8, I see progression groups in PF at all times of the day on Gilgamesh. For you to not join/create a progression party and ignore PF requirements, why did you not expect to get kicked and blacklisted? Those people clearly want to play with people who are as experienced as them, and regardless of if you want to call it being an elitist or not, that's what PF is for; to make your own groups with whatever requirements you want (hence ilvl requirement and other setting selections). Sure, it's your right to crash the party and totally ignore those things, but again, that's what gets you blacklisted and kicked.
As for why most people are impatient; If it took someone 20+ hours of wiping to learn and master a fight in a progression group, do you think they want to go through that every single time they want to attempt clearing it? I think we all understand that this is a game and it is essentially a time sink; it's just a matter of we don't want to have to waste even more time doing something that we're capable of doing in a much faster amount of time.
The TLDR:
If you join a progression party and they kick you for being new/bad, they're in the wrong.
If you join a farm/experienced party and they kick/blacklist you for being new, you're in the wrong (for joining when you're new when it specifically requests experienced).