Thing is, I can kind of see what people mean when they say it. City play with such a high line that when they lose the ball the defence is always exposed. It's the same kind of point when there's moaning about the tactical fouls - any team caught out high up the pitch will do that, but City by definition of how they play will be caught that way more often.
The Leicester game recently was a good example of that - although City romped home in the end, the speed of Leicester's breaks definitely caused City problems, and we know all too well that last season the slow full backs left City thoroughly open to conceding goals, albeit a keeper who saved one or two might have been a help.
So in a way, it's true, City can be got at, but you first have to get the ball of them, and then have to attack with real pace and precision when you do. But of course that's a nuanced position to take, which is why it's not that the comments are wrong, it's that they're grotesquely simplistic.