They did.
And they've admitted it, lol.
People who aren't in the industry don't understand. It's all relationships. Dame spent the better part of his career protecting people, and supporting people against the machine, but never got the same treatment in return. He doesn't play "the game". And anyone who's ever done business in music, knows if you don’t play the game, people will try to get you out. A lot of people turned their backs on dude because they needed to feed their families. Not because he did anyone dirty.
I remember being in meetings at Def Jam where people were literally joking about how they could get him out of the label. We also have to remember who's running these companies. It's not people from around the way, or even people from the culture. Erick Sermon said it best, he said he learned back in the 90's not to ever piss the wrong people off in the music business, because "even if you're right, they'll make you look wrong and make you the bad guy". Erick said Dreamworks tried to treat him like Dame Dash because he was yelling at white executives. They told him he couldn't come to the office anymore. Lyor and Doug both admitted that they felt Dame should be "moved out" of the business. Stoute said in interviews that he felt the same. This is what they do. Industry Rule # 4080.
Lyor was not even with Universal/Def Jam when Dame left.
He still did the DD music group after Def Jam.
And screaming at your partners and bosses, not attending meetings, being a self-admitted a$$hole doesn't mean that someone is conspiring against you.
It just means that perhaps they don't want to work with you because of you behaving badly. It's like pulling up to work like Dame and getting fired, and saying that the company conspired against you.
Dame was with Def Jam for years not playing game, nobody got rid of him cause he (or Jay really) made them a lot of money. When Jay-z didn't wanna be associated with him, he still had Cam and Beans, but when Cam left Def Jam. He was over, since he didn't bring in any money.
The music industry, like all industries, tolerate shyt when you bring in a lot of money.