Both of those sentences are what are wrong with gaming communities: 'iF yOu DoNt LiKe It JuSt QuIt". It's okay to have a differing opinion from other players in the community, or to question if the current state of the game is what is best for it. Diablo 3 is kind of stuck in a vacuum right now until Diablo 4 happens, it's clear that the amount of development time associated with the game is incredibly minimal and outside of extreme cases they aren't listening to player feedback.
Your last sentence may have been valid if you didn't add "Kappa" at the end like some twitch chat mongoloid. What you seem to lack understanding of is that POE is not about hitting level 100, it's about ridiculous build diversity, experimentation and having fun playing the way that you want to; which Diablo currently suffers from in their 1-3 valid play styles per class. I play/have played all of the ARPG's because I love the genre: D1/D2/D3, Torchlight1/2/3, PoE, Marvel Heroes, Wolcen and others that have come and gone over the years.
To the original question:
I don't think the stat grind is fun, but it enables some players to do things that are more fun for them: push higher rifts. I rarely go more than about 1k paragons in a season, which is not remotely high; but that's where my overall interest in the game hits its peak. I personally enjoyed it more when there were 100 paragon levels, because it felt like there was a goal to be attained. Now it's just grinding x more paragon levels until I do enough damage or have enough survivability to progress one rift higher, but for what purpose?
I feel like the end-game is missing flavor of some sort, it should not just be "grind paragon to progress 1 rift higher" to what... go up a leaderboard rank? There's only a subset of people that actually care about that and since the leaderboards are not true solo, 2-man, 3-man and 4-man leader rankings it's less fun for those whose goal that is since you can gain paragon levels dramatically faster running in a 4-man group and then dominate the solo leaderboards with it. I get it; anyone can do that but many solo or 2-man players enjoy playing in those styles.
And here is the winner!
Couldn't have explained better than this.