Yea, shit like that happens man. I think it really boils down to alot of things besides the musicianship or technicality of a band. Other things like Band Chemistry. Through the solid frienship within the band, compromise if there are different genre preferences between the band members. Talking it out is never easy but it just happens to be the only way it can be done.
My band for example, guitarist - effing good in my standards but he's into alot of old school stuff. And not just thrash man, he's still listening to Ozzy and stuff. Not that I have anything against Ozzy but I believe in moving on. So he's into old school stuff, Here I am trying to translate lyrics from Lamb Of God's Ruin. He's irritated, so am I. But the thing that keeps this band together is that we've been best friends for ages and thats where we compromised on a whole lot of things in our music. Vocals, riffs, blah blah blah. 7 Originals later(Which will be recorded after the O's, BUY WHEN OUT HOR!) We are both happy with our stuff, end of story. And hopefully nothing tragic to add to in the near future.