I agree with you here, something about healing isn't right at the moment. I'll go into matches with just two healers and not win because they heal each other and no one can get them past about 90%. Even with one healer you need like 3 DPS just to take them down because of this insanity. The worst part is that most people argue "Just stun them and kill them" but they've usually got one heal out by the time you can unless you're a stealth class, and if you can't kill them within the time frame of your stuns, they'll be back to full within seconds. Interrupting them doesn't work too well either because it only stops one heal, they usually have 5 others they can use instead.
My best solution involves something either getting nerfed or buffed to the point where healing can only outdo the damage of one DPS, because if you need 5 people to take down one healer, something's gone horribly wrong in the balance department.