they keep their older acts active and give them comebacks and promotions even if they are not at their prime or profitable anymore, unlike HYBE which would put you in dungeon if you didn't sell the suitable amount of albums or not successful enough. Or Yg which would outright dispose you off while debuting new group.
That's probably why SM has most amount of legendary acts still promoting in kpop industry.
Tbh seeing the post of formis-9 member made me think that what would happen to txt, enhyphen, lesserafim when they are not at their prime anymore. Would hybe put them in dungeon too.
And the amount of new groups they keep on debuting every year, it just takes the spotlight away from older groups