The WoT subreddit throws a lot of hate towards WG and the 268v4, and deservedly so, but I'd never bothered to check vbaddict til tonight to see how broken it was.
It's has the fifth highest win rate in the entire game at a whopping 57.2% (most tanks are considered OP when they encroach up around 52, 53+). It's also the most played tank in the top ten on that list by a considerable margin with 62k+ games played (the next closest is another OP tank which happens to be a premium, the 13 57, at 19k games). The only tank with a higher win rate than the 268v4 that doesn't have a small data set is the 907 but we know that's a CW reward vehicle so generally only better players have it.
So... in short... you have a vehicle everyone can get (and they have given how many games are being played in it) with a win rate just 1% lower than another already OP vehicle, the 907, which only good players have access to. That's pretty much the definition of broken/unbalanced.
There's no way WG is this clueless. They have to realize this thing is broken and are simply leaving it as is to milk the inevitable cash inflow players are throwing at premium time/free XP conversion/whatever to get to it.