Turtles did okay in 2012 without Splinter, right?
Of course, as soon as Splinter passed in Mirage, the family split up... and Mikey STILL hasn't made it back to Earth.
In most iterations, Leo is the one who holds everything together.
When Mike split off from the family in IDW, it didn't ruin everything. Whereas Leo and Don getting brainwashed/shellshocked by the Foot DID. And everybody was fine without Raph's grumpy ass back in the very beginning.
