They’ve been very hush hush about him in the new canon (if I’m not mistaken, his brief appearance in Battlefront II might be his only out of film appearance). But I don’t see the issue. He was clearly Snoke’s right hand guy like Vader was to the Emperor, and he could pretty much kill anyone who stands in his way (as is demonstrated with Hux).
Darth Vader eradicated an entire organization of trained force users. In his previous life, he was a war hero. Darth Vader had clout to lead the Galactic Empire should he chose to. What has Kyle Ren accomplished? I’m not saying he hasn’t proven himself worthy of the position he now holds in some off-screen way, but they’ve done nothing on screen to give him the position other than kill Snoke to impress a girl.
Honestly Kylo Ren has also eradicated an entire organization that was being led by a legend.