It does have some effect on corner cases.
Say you're playing some genesis wave/elf deck. You have 10 various elf creatures and 20 cards left in your library. If you cast a wave with x=7 and procede to hit 2 or more Regal Force.
At regular REL you will deck yourself (12x2 > 13) but at competitive or professional you have the ability to simply ignore that and safely beat face.
Edit:
This has no effect on FNM. It only affects events like PTQs, GPTs, PTs, etc.
if your opponent notices this they may bring it to your attention and you will have to draw your cards however.
Has anyone though about running Rule of Law in the sideboard? A lot harder for combo to deal with than Cannonist as it doesn't die to their burn spells.
if your opponent notices this they may bring it to your attention and you will have to draw your cards however.