In the end, they are often forced to sacrifice a Pokemon in order to Defog.
Considering that the HO player sacrificed Deo-D to get the Hazards up its fine if you have to sac something to get your defog/rapid spin, your still even with the opponent. However, if you manage to get defog off without losing something you have the edge and with smart plays thats easily possible. Given how predictable HO is you can make it even worse for them. Example, Sub Punch Mawile as a lead and HP fighting Latios as a defogger. Mawile attacks round 1, if there is no red card/taunt set up a sub on turn 2 and kill deo in turn 3. That way you basicly start the match 6 vs 4 as the opponent pays for every layer of spikes with one poke. Then you get Latios in on lando or something and kill Bisharp on the obvious switch in with HP fighting (the HO player is forced to bring Bisharp in against a defogger otherwise he risks losing his hazards for nothing) then proceed to defog. That way you would have a 6 to 3 lead without any hazards on the field, show me an HO team that comes back from that.
I know thats a specific scenario but the point i am trying to make is that its not only possible to deal with Deo-D without falling behind, its even possible to take advantage of it to the point where you have an autowin against HO and you dont need some gimmick sets/mons for that, i am talking about A and S rank threats that can do that.