TwoHeadsBarking
First Post
I'm not sure what kind of campaigns you're playing in where the clerics are doing crazy damage. This ability makes it not matter how long the fight "drags on", because it's handing out constant healing as an at-will. In addition, it makes it easier for everyone to hit. After you hit once, you gain the bonus to hit as well if needed, making the cycle even easier to maintain.
If there are multiple enemies on the field, then taking a long time to kill one without expending resources means that the rest get more time to plug away at everyone else. Seal can only heal one ally, while every living enemy has a change to hurt an ally. And most, if not all, solos can hit multiple targets at once. Also, when enemies live longer they have more chances to disrupt your plans with nasty conditions, recharge powers, and complete evil rituals that you are trying to stop. So yes, the length of the fight is still important.
The cleric could have been using Sacred Flame or Recovery Strike to do damage while defending, or Righteous Brand or Lance of Faith to do damage while helping someone else attack. And no, I haven't seen leaders whip out huge amounts of damage, but their attacks aren't nothing. Most non-strikers struggle to do more than [W] damage with an at-will.