Pentamelds are not "required", but most groups are going to tell people to pentameld if they are serious unless it's weeks into the tier and folks have decent gear from other methods. It's been that way for years and the only time it wasn't the case was probably the first two tiers I ran during shadowbringers, long before they allowed DC travel and it was a different culture then.

The issue with basically all the "we put this here for end game so people grind and keep paying a sub" content is that it is strictly worse arcade game style artificial difficulty by making sure that there is no way to know what is coming until it hits the player and making sure that hit causes a restart of the fight. It is strictly worse because it takes 8 people organized to do the content with specific roles, which also takes time to recruit for, and the length of the fights with no rewards for partial completion. It's an all or nothing gamble and it causes a lot of friction between players because of it. Also the skinner box style / sunken time fallacy type of binding that drives the content has a double edged sword kind of effect. If someone drops out over an extended break, they basically are less likely to come back after seeing it for what it is. FFXIV *was* the lesser of the two evils at one point but now kind of is the evil since all the other ones dropped out of the race.