When a dps has hit the 50% penalty it's not worth the mana to raise them. Especially now that mana is capped and a rez is 25% of our total mana. That gets drained quick with multiple raises.
And healers will generally wait for a swiftcast so they're not spending 10s on a raise cast time. Time they could be healing other players, healing the tanks, or doing more damage than said dead team mate on the floor.