Yes there is blobbing in this game, that "blob" is your ARMY. and it makes perfect sense to "blob" your army together, would you rather split all your units up and lose them 1 by 1 like an idiot? i'd like to think not
Most people just throw the word around as an excuse for their incompetence, and a way to destabilize their opponent.
Someone who accuses another person of blobbing is essentially saying: "You're not playing the way I want you to play." And that is kind of the whole basis of a strategy game.
Are some units overperforming while others are underperforming? Absolutely. But that has nothing to do with the word "blobbing" and how it gets used.