Can we see proof of player loss? like proper hard stats? Because i am sure the dropoff we see is people sitting accounts. Like reaching a certain ranking on a account and not playing anymore to retain the rank/mmr. Happens all the time. Also changes bring more people and then you see a drop off, pro games too as most don't watch through client and some people don't get the boost or hype to want to play more after watching them.
It is like the WoW effect. Every new installation brings people back, then they leave. Some stay, some leave permanent. Mage changes really did hit us Mid players hard, some adapted (like myself) others disappeared or changed role (seen many people i know do this, many opponents).
I doubt the DQ was the biggest factor. It is just the loudest of the group, it is the boogey man people want to blame for people leaving or just a normal flux in the playerbase. Every game has this happen, this game isn't the only one. It has been around for YEARS so of course some people will give up on it, technically we are seeing the curve of babyboomers of the first gen of this game finally dying from old age. Some just can't keep up with this game, are too stressed, too salty or just aren't 100% anymore and know it. All sports or games have this.
SO WHY ARE WE ALL MAKING A BIG DEAL LIKE THIS IS A NEW THING. MJ isn't playing basketball anymore right? What makes you think people aren't finding a reason to retire?