It actually goes prior to that, even when the game was announced at E3 2014 the press release said that destruction would be a separated online mode.
What did seem to be changed was that in 2014 they destroy a building to attack a kingpin, in 2015 they said this didn' worked in the campaign and that instead they would have a nemesis like system for taking the gangs (which is still in place)
Yeah, it's been there to know for those of us who weren't so agog by the concept to know pretty much all along. The teaser shown back then didn't make the distinction, but then again, it was just CG so I believe were just guessing that player-controlled building topples were a think when we
first saw the clip, and then I assume word got out that it really happens in-game and yet not enough clarity of PR came with it. Then that kingpin-dropping thing, that's what got me in that Gamescom playthrough, that they were describing enemies being in a stage and talking about "multiplayer". I already know Crackdown to be a multiplayer experience from co-op predecessors, and they had no other footage or talk of the game to isolate the modes, so it just clicked into reasonable place.
It's personally been a bit of a shock after having some intuitive understanding of what Crackdown 3 is going to be that is not what Crackdown 3 is going to be. But it's fair to say i miseld myself, although I don't think the MS PR has done a great job of explaining the mode structure and mitigating expectations, especially during its building-toppling wowwer broadcasts. Them labeling "Wrecking Zone" mode will I hope help. Better now to clear up than to have pre-orders sell through and have consumers be pissed.
What they showed was the single player campaign.
...Which is designed to be multiplayer.
(Also, the Campaign trailer was demoed as "multiplayer", assuming the other Agents were not bots. So, not much help in clearing things up there. Little about that trailer screamed "Story Mode' or "Single Player", it was just shit being thrown around and blown up and jumped around on for fun in the third of a franchise of co-op shit-blowing-uppers.)