I would love to see a completely ad-free internet and cryptocurrencies give me quite some hope that this might actually become true.
As such they are big threat for the business model of internet media giants. If I were in their position I'd do anything to slow down their evolution. While the advertising ban may affect some scammers, it also damages the reputation of crypto in the eyes of the vast (uninformed) majority.
Even better if I can disguise that blow as a "protective" measure towards my audience.