That's certainly true, but at the risk of getting off-topic, you'd be... living dangerously, let's say... to trust the form to check your data integrity. So you're likely going to be checking it server side anyway.

Personally, I like to see that included in forms, not for any application logic or dubious security reasons, but for the general level of ill will you'll generate by silently and ruthlessly obliterating the input from valid users. Preventing such behavior strikes me as a goal of both the presentation and business logics anyway.