SM was much more dominant in earlier gens, so that many famous idols who have now reached the age where they can be respectable judges that are clearly older than all participants (say: above 30) are from SM.
Once 3rd gen has aged and stopped being active in their group, expect BTS, Twice, BP, MAMAMOO members etc to also be asked for these kind of things.
That's my point. Some gens later, I think Hybe idols gonna be common in these shows, since they are moving like 2nd gen SM.
Judge and master gigs are related to popularity (even if some of them are based in talent too). Even outside big companies, Uji is a better singer than Solji (and Taeyeon, and many other popular idols), but we will never see Uji as a judge or mentor since Bestie had no impact, Solji was a mentor in Boys Planet.