Richard Williams' music blog The Blue Moment is full of excellent stuff, some of it grounded in his time as an a&r man for Island in the 70s.
Writing about Television he says "no band can last long with two leaders".
This made me wonder if there are any exceptions. The big exception is the biggest band of all, the Beatles, but you might say that by modern standards they didn't last all that long.
It's clear that no decisions can be made within the Rolling Stones without Mick and Keith. However the former proposes, the latter disposes and they both know that they're useless without each other. Robert Plant and Jimmy Page wrote Led Zeppelin's songs and formed their front line together. When Cream were together both Jack Bruce and Eric Clapton seemed to take the weight of public attention equally.
The leadership of REM seems to be a triumvirate. All their songs are credited equally, as are U2's and Coldplay's. This means that all the members share in the really rich source of revenue, though not necessarily equally. This is certainly why they're all still together.
I can think of one prominent exception to Richard's Law. The career of the Eagles is interesting in that when they did split up it was nothing to do with warring between their two leaders, Don Henley and Glenn Frey. When hell froze over and they reformed they slipped back into their old roles. But watching their official documentary the other day I got the clear impression that all the other members of the band, whether past or present, were very aware that they served at the pleasure of their two leaders.
Obviously there are always exceptions to any rule but the rarity of these makes you think.