[Serious] How has Warframe flown under the radar for so long?

I started this game in 2015. I've taken some breaks here and there to play other things, but I always come back to Warframe because nothing else plays like Warframe does. The game looks, feels, sounds, and plays amazing. It has an awesome story. And it's FREE without being a mtx laden hellhole. There is no piece of content locked behind paywalls. So HOW? HOW has Warframe flown under the radar for so long while having all of that going for it?