Do people in this game not comprehend the concept of shield healers?

[Rongway]

casting their shielding spells after the attack hits, which is pretty pointless.

If you're precasting a shield when people are already full, you're wasting the direct heal portion of the spell. If another AoE is coming within the next 30s, it's better to cast the shield spell after the first hit so that you get the full effect of the direct heal and also the shield.

And of course there are lots of cases where an oGCD will do all the healing you need without you having to stop to use a shielld at all.

Shields are only worth precasting if you would die without a shield.