You can say that players are divided in two groups who grind for exp to get that paragon 1000 (thats me) and people who like level cap at 100 and perfect their gear.
Why not to accommodate both? You can grind after 100lvl to fill whole paragon board but if you play multiplayer or pvp than you are capped at lvl100. I prefer solo experience and sorry but when that blue bar is moving i wanna play more. Griding just for gear its fun but not as much paragon 800.
When it comes to leader boards, Last epoch had a good idea. When you create new character you can chose if you want seasonal character to climb leaderboards or seasonal character without leaderboard.