There's a good chance that with the long cooldowns and the loss of DPS, having someone play a dedicated support role won't be enough to outlast pressure from the other team anyway.
You can take my quote about "teams" and apply it to PvE and WvW. I didn't mean it to be PvP only.
Edit: I'm bored, so I'll go more into the PvE process.
What ANet basically wants to do with their higher level PvE mobs is have them work a lot like player characters. In this case, it shouldn't be too hard to give them as much cohesion as pug group dealing with the event in question. This can be debated, but they do have somewhat of a track record with GW1 and we don't have enough recent hands on time or footage of the harder areas to make this call.
From there, you go between Dungeons, and Open world. In the Dungeons, you're attacking, so if you can't outlast their pressure you have to retreat. But then they heal up as well using the same out-of-combat rapid regeneration system. If you can outlast them, that means their pressure was low enough that your level of DPS was enough, in which case it was probably an easy fight even without all the support skill spam.
In the Open World, the main issue is with the Dynamic Events. For some of them, just weathering the storm will be enough. For others, there may be an objective, like the enemy is trying to kill, steal, or kidnap something. In other cases the enemy may have heals, and there will be cases where you are given a literal time limit. These are all things that can make being support oriented an impossible way to win the DE, or it could just be a way to slog and slow it down. But if the case was that you were just making something take forever, you will also have to deal with possible consequences such as a boss having so much health that it takes 30+ minutes to take him out. For an example, IGN has a 20 minute long Mesmer video and at least half of it is just players whacking on a boss with tons of health. Imagine event bosses in the higher level areas. The large time commitment will naturally give players incentive against such a low DPS strategy. On top of that, if you have parallel events running, being clogged up on one event may cause losses in the other events, although this fact may end up applying more for WvW than PvE.
Quick Version: I should have typed "other force" in my original quote. There are many ways to make support builds nonviable or at least extremely sub optimal, with objective based gameplay being one of the easiest methods.
