I suppose you could tax a proportion of your profit at a higher rate, according to the proportion of your revenue that came from advertising.
But advertising isn't a "free cash stream that can be bolted on everywhere". It's part of a business model that either is sustainable or isn't.
If you taxed it that much higher, a lot of businesses would simply go out of business, because people aren't willing to pay a subscription instead. Especially businesses that survive on a lot of users who use something only occasionally. Is that really what you want? Think carefully about how much journalism would be even further eroded...