That's because everything in 40k is mary sue as shit. It works because it's all in the same universe (except Draigo, he doesn't work anywhere). In any other universe most of the things Wahammer does would fly about as far as a brick.
At least our Hiveminds don't fall in love with imperial soldiers as a main plot device and actually act like the world eating alien menace that they are.
What about Starship Troopers ? Aliens aren't the base for Tyranids. Its Starship Troopers. Their creatures do have more types for combat than Aliens and they have proper psychic link. Not the animal type.
Yeah, I've seen this article too, where some whiny mon'keigh with very approximate knowledge of what Warhammer 40K actually is, is speculating about what comes from where. Tyranids come from Starship Troopers, he says. Wait, what exactly do they share with this short story by Heinlein? Only the idea of planetary infestation and being ruled by the Hivemind, how original. Beside that, the general design and the entirety of visual designs for Tyranids were totally creative work of GW authors and artists. But Blizzard guys took both the idea and the visuals from GW, shifting a bit here and there - and heer ve go - Zerg! What you need to do, just stick infested girl in this, and you win. Good job, worldwide fame.
Well, it suits better than Aliens thats why they went with Starship Troopers, its hard to put Tyranids anywhere after i read all about them. Genestealers and Bio-titans, feeding spirals and so on. These can't fit anywhere. They have a certain logic and progression behind them, especially Genestealers but it somehow ends up Mary Sue to some people. Time frame for infestation takes a long time. So does the Genestealer Cults. You should see the article written by the guy who didn't know about Warhammer 40k and said it stole from Gears Of War. These are the people who claim to be Game Journalists by the way...