I mean. We could sacrifice the goalkeeper too if attacking threat is all we are interested in.
I now see how a back 3 isn't always more defensive. What I fail to see is it not being a suicidal tactic when it comes to defending crosses into the box (one of the most likely ways we have been likely to conced in recent years - Lord knows opposition teams rarely cut us open, it's set-pieces and headers which tend to be how we concede).
Not only that, but by losing a centreback we make ourselves easier to defend against at our own set-pieces by omitting one of our 2 main aerial threats.