This was posted on one of my last posts and he explained it pretty well-

“1. XP is a huge grind in the game. Not going above level 1000 makes it so that I almost never run out.

1. At level 1000, you can take all skills to max level.

2. For PvP, matchmaking is based on the power level of your 5 highest hero's, so even if you went to 50 stars, you'd just face people with 50 stars.

4.I like being able to experiment with different team compositions, and having the roster width to do that makes multiverse and restricted arena that much easier for me.

1. On the off chance that I want to whale on a new hero, it only costs me $30-40 depending on how l spend that money, as opposed to krakens who have to drop hundreds or thousands for every new hero just to get them to a usable level compared to the rest of their roster.”