I don't think it's video games, I think it's based on competitive MTG. There was a 4chan leak -- yes, I know, stop laughing -- that stated that GW wants to move towards a MTG style business model. Where instead of 2000 points of Tyranids (since at that point you aren't buying more nids unless something new is put out) you'd have 500 points of Nids, 500 of Genestealers, 500 of Guard, 500 of AdMech. That gives them 4 different armies to sell new things to you, and if they make some of them no longer playable or only playable in legends or whatever, you're given a subtle push to swap those 500 points out every so often.