So some players will never try because they don't know they can, and how about the ones that do.
Say the first time he tries the wizard isn't casting a full round spell, so the DM rightly says sorry the wizard gets the spell off before you can react. You need to ready an action to interrupt, learning more rules... which if they had known beforehand, they would have been successful.
Next time they ready and action, but the wizard doesn't cast a spell, and their ready action is wasted, so they think it isn't worth it.
Then the wizard casts a full round spell and they don't even think to go and interrupt him because they don't know the rules about full round spells as they aren't the wizard so never needed to learn it.
There is a whole load of interactions that they are missing out on because they don't understand the rules of timing and actions full, just enough to get through normal combat.