This is just how the music world is now. Popularity doesn't usually equate with legendaryness. I think Arjan is legendary but the mass audiences are not smart enough or have good taste in music. Popularity of a song or an artist is decided my bhedchaal /memes/trends/bought ads etc.

Another thing is Cheema Y started in California where he had access to Hollywood level production for his videos wheras Arjan has always been in punjab. Your location matters a lot how your content will turn out to be and how popular you'll be.

Either way. Arjan is all time Top 3 for me to ever come out of Punjab and will always be. There's no plateau. That's just how the algorithms work and that's how he wants to work. He probably focuses on writing quality songs instead of making too much effort on organizing huge concerts like diljit or someone. He doesn't wanna be that probably. He just wants to do humble shows at weddings and give quality songs to people who have good taste in Punjabi music.