I'll try to hold off on my snarkiness and answer your questions plainly.
Not everyone realizes this, but for their entire recording career, Grandaddy was pretty much a one man band, essentially Jason Lytle's solo project. He wrote and produced pretty much all of it.
He played all the instruments. Aaron played drums. Gary Young recorded street bunny.
You can read about how the lack of collaboration caused dissention in the band here in this Jim Fairchild interview where he discusses the process of recording Under The Western Freeway and SSlump:http://rocksucker.co.uk/2011/09/intervi ... daddy.html
My own theories about this concept:
Worked well at the beginning because Jason Lytle was young, brilliant, and unstoppable.
Later it led to the band's demise because they were stuck in a state of non-collaboration.
The difference with Fambly Cat is that the band never learned the songs to perform live.
I was disappointed that they didn't play any of those during their reunion shows. I'm a rare grandaddy fan that likes Fambly Cat a lot more than Sumday (but that's a different story).
Jason Lytle solo albums are not much different than Grandaddy albums.
To compare grandaddy to some other somewhat similar acts...
Wilco: Jeff Tweedy is the writer and visionary, but he knows how to benefit from collaboration and gets some great people to play on his records. Getting Jim Orourke involved with production was brilliant. Jason Lytle could have really benefitted from that kind of thing later in his career.
Mac Demarco: i don't think I can convince the radiohead centric fans this, but Mac Demarco has s hell of a lot in common with early jason Lytle. He writes, plays, and produces his albums all by himself. Then he teaches his songs to his lovable band mates to perform live. He's more transparent to bill the records under his own name. He's still in his hot streak now. Catch him before it's too late.