As far as "nothing new," it's nothing new that if other opportunities had taken off, none of these guys would have needed STP. The band did not hide that if Talk Show had taken off, they wouldn't have had to rely on STP. same goes for Army of Anyone. If the production career had taken off, they wouldn't have needed to rely on STP. If studio time was something still in high demand, Kretz wouldn't have sold Bombshelter and returned to STP.
Same goes for Scott. If 12 Bar Blues went whatever platinum, he wouldn't have had to rely on STP. If Velvet Revolver didn't get torn apart, he wouldn't have needed to return to STP.
Anyway, the 20 years argument holds no water. First of all, Scott hasn't been a mess for 20 years. Even at times when he has fallen off the wagon, he has shown up and could perform. But it's only in the last five years that he's really had major issues with showing up on time, being able to perform at the level expected, and even showing up at all.
We can say, "Oh they've put up with this for 20 years. To say something now is bullshit." In what other universe would this argument be reasonable? The thing being missed here is that things change in 20 years. When you're 29, it's cool to party before a show and maybe show up late, it's funny to do a show drunk, and no one is think about what their income will be like when they can no longer perform.
For Robert (47), Dean (52), and Eric (47), it's no longer acceptable to party before a show. It's no longer acceptable to be drunk on stage. Income during retirement is on their mind.
For Scott (45), this is something he has been unable or unwilling to control. He continues to party before shows. He continues to do shows fucked up. He isn't even concerned about retirement, he's concerned about the $60k he needs each month to maintain his lifestyle. These are marked differences in what constitutes acceptable behavior in a band.
In no other business would this be a discussion. If four friends bought a sports team and things went great, but then one guy started no showing to board meetings, showing up drunk, making bad trades at night while high on cocaine, would we say those other guys have to stick it out with the fourth guy? Of course not. Who cares how long that guy has had a problem and how long they've dealt with it. If the other 3 guys feel the product is being diminished and they want to bring in a fourth owner known for success in the sports world, no one would blink an eye.