It's the progression and 'loot' system (I say 'loot' in quotes because it's not loot, it's glorified gambling).

Maybe this is just me being an old person now, but that progression bar at the end of matches sucks the joy out of them. If I lose, I can only think of how much farther the bar would have gone if I had won - and if I win I don't care because I'm still really far away from my next 'loot' box.

This ends up translating to mid-match rage, taking losses or screwups by myself or my team more hard, just because I know it'll then take longer to get the next damn skinner box.

And yet the 'loot' boxes are borderline insulting. Not only is the 'loot' heavily skewed towards icons, sprays, and voice clips (admittedly, those are the easiest to create) but they'll give you duplicates and only refund a minuscule fraction of the 'purchase' price to you in gold. Like I was selling them to a trash vendor in WoW or something.

These 'summer games' have made it even worse. Because they've added cosmetics that you cannot buy with gold, and then stuffed them all in special 'loot' boxes that drop one, maybe two of the unique items at most. So if you want a particular item? Well, good luck.

Bah... I dunno. I know these 'loot' boxes probably make Blizzard a huge pile of money. But all I can do is pine wistfully for the days of Unreal Tournament and Quake when you played a game because it was fun, not to get levels or unlocks or shiny flame skins.

If you're able to play the game without the progression bar and 'loot' system bothering you, then more power to you and I wish I was in your shoes :)