I've been noticing this more and more as well. I recently played against a deck that dropped 3 questing beasts back to back after I killed them off. Then I started to notice the trend. It seems that I play against opponents who feel like they're playing a 20 card deck. I see the same exact cards every game, and back to back as if they're only drawing the best cards in their deck and on curve.
Dunes of Zairo
SHANDALAR
Innistrad - The Darkest Night
~THE RAVNICAN CONSORTIUM~
A Community Set
Commander: Allies & Adversaries