Hi..it would have been better if you had posted any specific doubt. But coming onto the logic:
A magazine X has allowed a company Y to use its name. Now, if magazine X advertises Y's competitors A, B and C, then A, B and C may withdraw from advertising with the magazine any further. And hence you have got your answer i.e. a factor which may lead to reduced revenues for magazine X.
Hope that clarifies.
Gaurav
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