Healers have everything to do with what’s being discussed in this thread. If the Druid is a powerful enough healer that they are required to complete content, and cannot be viably subbed with other classes, then there is a major conflict with the game’s design philosophy.
Healers have nothing to do with the argument that I responded to, which was that ten thieves (or any other group comp using ten of the same profession) ‘must’ be able to complete a raid.
I’m not really sure what point you’re trying to make there. It looks like you’re trying to say that taking two of the same profession automatically means a DPS loss, which makes no sense. If you’re dropping one profession (1 player, or mulitple?) for another profession, your gain/loss in DPS is going to depend on which professions/builds/roles those are. They all have different levels of DPS, support, and survivability.
What I am saying is that every time you exclude a profession from your raid group in favour of a different profession, you should end up losing out on something that you’re really going to miss, and ultimately, that almost invariably has to mean that one way or another, you lose a nice, fat chunk of your practical raid DPS.
Why?
Because the typical raid encounter can be reduced to a pretty simple question:
“Can you successfully deal with these mechanics while maintaining an average of at least x DPS for y time?”
If you can answer ‘yes’ to that question, you win. If you can’t, you wipe and will have to try again.
Everything about any fight that follows this formula ultimately boils down to either increasing your raid’s DPS or avoiding the loss of DPS.
The entire design philosophy of GW2 is for the profession to be balanced with each other so that any party composition is possible. That a certain profession or mix of professions is not required. That 10 of the same profession can complete any content, even if it’s not likely to be the best/fastest/easiest. In fact, that was a specific thing Anet was showing off before launch. Being able to complete dungeons of 5 of the same profession.
Whether you agree with it or not, or whether if fits your idea of what profession balance is, that is the intended design of GW2. Or at least it has been for the last 3 years.
It’s never really been the intended design to that degree — what they’ve promised is that you shouldn’t have to wait around for a member of one specific profession, and all signs point to that continuing to be the case.
But that doesn’t mean that full groups of ten of the same profession can or should be viable in all conceivable PvE content. That’s taking the original idea to an extreme.
It might be different for open-world, dungeons, and even fractals, but I would expect raids to be tuned in such a way that those comps aren’t viable, simply because of the practical DPS losses incurred by excluding all eight of the other professions.