Warframe has been in a playable state since 2012, although I didn't start seriously playing it until 2014 (the year D1 came out) but from what I can remember of the primary differences between Warframe 2014 and Warframe 2018. They improved the parkour to be a bit easier and more fun. They Added ADS scopes for sniper rifles. And they added the relics system to improve prime part loot pools from the watered down garbage they used to be. What exactly did warframe steal from destiny to compete with destiny?
I'm not bashing you for your opinion, I also enjoy Destiny's gunplay and some of the raid mechanics I remember having lots of fun with the vault of glass and kings fall. And the destiny lore pulls me in as much as the warframe lore.