Why wouldn't a company monetize both ways? Paid video streaming services still show ads, and when I pay for a movie in theaters, they're still doing product placements.
It makes the service worse. I won't pay for a streamer that uses ads. If they start doing that I'm out. Ofc, that doesn't mean it's not a net win for them across all customers, but it does mean there are a subset of customers who are now willing to pay for a different service, and the market has an incentive to service that.
