How is it possible?

I mean the actual bullshit here is that you get absolutely no feedback from Valve. They don't tell you when you enter shadowpool, they don't tell when or even if you will get out of it and on what condition; meaning there is no incentive for you to play nice. They don't explain to you how it works or who they put there, e.g. evidence seems to indicate that often they prefer to put scripters in shadowpool rather than to VAC ban them. The steam support doesn't know anything either. It's very likely intended that they hide all this information on purpose: the uncertainty is enough for the player to not desert his account. Although if they're actually preventing you from climbing the ladder, that is really shitty.

/r/DotA2 Thread