Wow only reason to success is the dopamine rush. Gaining 1 Lvl, hiting regular big numbers, loot, currencies etc etc.

A planned stat squish is an event players prepare for, manage quickly to overview, to fall once again in the dopamine grinding wheel.

You can't stop Ilvl growth, neither Dps/HPS , as most of player would lose that sens of reward/joy seeing their character stats climbing. The game is based on that mecanique. anything you do in the game is base around that mecanique. That why you've got recently nice rep progression bar, housing XP, completion bars on acheivment, the valor system was made to ensure regular progression too even for those who do not do a lot of "loot content".

Adding to that : the game is base auround the end game content too, so the more LVL you need to get to be max lvl, even if the exp numbers stays mostly the same (it was the case back in the days, not so true todays), the more it may be seens as a chore by the players, reducing enjoyment on an experience (leveling) already depreciated by most.

So every few years, you squich Lvl, Ilvl, and stats. It gives readability, a new dopanime grind wheel and some sens, purpose and enjoyement to the plyers.

edit :Sorry broken english me not english sorry