Two points, to asdf and Vemi.
1. Valve created CS:GO and also TF2 (I am lumping TF2 in here because a similar thing happened a few years back with "fake unusual hat" plugins). Therefore, if they want to make a rule stating you can't use plugins to grant fake items (because those items are part of an economy), then they can damn well do so.
2. Community servers don't need fake item plugins to sustain themselves. I've been running TF2 servers for several years without fake unusual hat plugins (never once used one) and my servers are doing just fine and I get plenty of donators without having fake unusual hats.
I've been commenting on the Reddit thread and I'm honestly appalled by the CS:GO community's whining responses to this. It's like they're a bunch of 13 year old boys whose secret stash of Hustler magazines just got confiscated by their mothers.