It is not just this opening line. The openings I meet on chess.com are entirely different than those I meet OTB. For example I meet a lot of Exchange variations in the French; I get e3 by White in the King's Indian and 3. Bd3 in the Pirc. The Center-Counter/Scandinavian is very popular too. I even meet 1. d4 e5?! quite a lot (and at bullet I'll even lose to it!).
These are all rare (or non-existent) in OTB chess. Instead I see a lot of Tarraasch and Classical French , Main line and Saemisch KIng's Indians, Classical Pircs.
It´s just a move, you develop a piece and prepare castling, in addition, you avoid to fall in your opponent preparation, where is the fun of playing "sound" moves (2.Nf3 3.d4) if your opponent has memorised 15 moves of a main line and you'll find yourself crushed anyway? At least you are getting a game in fair terms. By no means is a bad move or a refuted line, just turn on your engine and check it yourself.