Soulframe and Warframe share a lot of things, including (very likely) being MMO looter sho- eh, slashers? So Soulframe is going to compete with Warframe, DE is going to try and draw from the Warframe playerbase to fill the Soulframe playerbase because few people are die-hard enough to actively grind two MMO-like games.
The other draw of Soulframe is clearly its Souls/Borne/Elden Ring inspiration so I think DE is banking on taking a slice of that demographic as well. Problem is, those players can just keep playing their game. The combat, movement, mechanics and level of polish in Soulframe is still leagues of difference compared to Elden Ring. "Do you like Elden Ring? Well play this game! It's almost like it!"