how is no one talking about

There is a fan theory going around that the Rick we know came from another reality. In that reality that he came from, he was part of the family's life including baby Morty.

In Rick Potion #9 we saw how Rick Cronenberged the whole world so he and Morty slipped into another reality where that reality's Rick and Morty were killed. So with that in mind, the theory that "our" Rick came from another reality holds water.

This has been partially covered on the show. It's been mentioned that he's been absent for about fourteen years, so whatever caused Rick to leave them (whichever Rick it may have been), that comfortably could've been shortly after Morty's birth. The show isn't always consistent with timeline, but this item fits itself so far.

My guess, Rick's long absence will turn out to have had something to do with Evil Morty.

"Here, with a special report, is a midget in a bikini."