No wonder you're against it, you don't understand it.
So, all of the other formations (4-4-2; 4-4-1-1; etc.) that were used before the so-called discovery of 3-5-2 have never been sussed then? Are they all not more useless for having been around for longer (apparently)?
Is that really how you think it works? How about looking at it differently:
when we have possession, the WB's pile forward making a 5 man midfield.
Usually it is just one of the WBs who piles forward to create a three man attack; he should already be in a midfield position.
When defending, they drop back to form a 5 man defence.
Yes they might well do that, occasionally, when we are well and truely under the cosh, but the manner of defence that should be the aim is something different. There are three CBs and three CMFs for a reason, they, along with one of the WBs should be the options to drop in to cover; those players that do not (and should not) drop in are your counterattack, your aggressive defence. When you play a team that puts you under so much pressure (under the cosh) you end up using both WBs as FBs and having CMF compressed back then you have the wrong shape - change your shape, but will all players then be in their natural positions? We have seen Bruce do this to good and bad effect.
Our problem was that our WB's didn't get back quick enough, leaving a gaping hole in the wide areas.
It's why there is the luxury of three CBs.