There's a huge difference there. Scooby-Doo and the Harlem Globe Trotters are not DC owned characters. They may have crossed over with DC characters at one point, but they are not actually a direct part of the DC Universe.
If they're gonna start infecting it with Cartoon Characters, then I want the Harlem Globetrotters, Mama Cass, and the Robo Stooges.
since they interacted with Scooby Doo, and he interacted with Batman.
If they wanted to do Superfriends, then they should've started a Superfriends line.