Why do casuals act as if it's the end of the world when suggesting?

[Allegor]

[I]
Since we're making assumptions here, I'm going to assume you're the kind of person that slams Medica 2 at least two times for any raidwide, followed up with Assize (because you've been holding it for this very moment instead of using it on cooldown) and Asylum to patch up any minor booboos, leaving your co-healer with nothing to heal.

Then you look at your co-healer and say "Hey, thanks for the healing NOT!" and walk out of the duty with your head held high, knowing you did a good job.

While ironically proving that there's largely no need for 2 healers in most non-high end content.