Sources connected to CBS, NBC and ABC tell TMZ ... the Peacock network believes Jimmy Fallon's ratings success gives them extreme bargaining power. They put the word out to celebs, agents and publicists ... if they want to be on Fallon they can't appear on ANY other network ... and not just shows that go head-to-head with Jimmy, but morning shows as well.
That is going too far... I could understand same day (i.e. appear on CBS in the morning and Fallon in the evening), but there has to be a limit as to how exclusive.
I was at a local concert once (the gal's name escapes me at this time), but she said she was ruined pretty much because she got stuck in traffic and was unable to get to Leno in time as the musical guest. It burned every bridge she had...