There are far fewer cards in Destiny than say magic, even when just looking at what is produced on a yearly basis. So having close to a play set of cards in Destiny is a lot more doable than Magic, which is hard to have a place set for, specially since you need 4 cards not 2.
So yes, Destiny is a small CCG in comparison and one can manage a play set. Also, since is a smaller game, a particular deck gets older much faster, so people tend to play more decks, leading to the need of a play set. A play set is certainly not required, just one deck and tokens.