The difficulty is reversed and the philosophy is all wrong.
Making the game easier to solo and then capping participation at the end game creates all the toxicity the game has today.
If everyone can progress alone nobody is compelled to socialize.
If end game is designed around instanced play and the roster is limited to X number of players the leader is only going to get the very best of X.
So all the hate on raider io, the hate on party and raid leaders being exclusive, the hate on casual players being bad at the game, the entire dismantling of community in the game, the lack of a living breathing world, the time gated content, etc, etc. Literally ALL of the problems that aren’t class design problems are rooted in this design philosophy.
The better philosophy is to make the game difficult for everyone. And to remove the hard cap on participation. There are different ways to do it but the end result should be a product that heavily encourages people to work together to do things.