It is a grind on top of being pay to win. You have to buy the equipment and then level it up on top of it. Have you even played Warframe? They even release those prime packs with exclusive stuff to try and get people who are willing to grind that long for even more money. f2p with pay to win models are considerably worse than a game where you buy it and adds microtransactions later, p2w completely ruins any competetive atmosphere for a game. Which Warframe never really had one to begin with, it was just PVE content with Pay to win right from the get go. In Warframe a person just playing the game can buy better equipment than someone who has grinded the game since release, they don't have to work for the equipment other than leveling up cutting the grinding to a minumum, which can be pretty much excluding to leveling up warframes and equipment. Not to mention the advantages of paying for other stuff, heck the more I remember it there was a literal metric crap ton of stuff you can just bypass by buying stuff.