> what are the issues of implementing fee-for-service on the internet?

If you aren't selling porn or whatever credit card companies can't stomach, there's no problem. I recently stumbled upon a way to accept payments without the credit card companies (crypto): https://www.x402.org

> what would be the side effects of a banner ad type business model?

I remember Carbon Ads and BuySellAds being tasteful banner ad companies. I think one or both folded in recent years. In today's era, respectful banner ads probably have a niche market, especially with the prevalence of ad blockers. You'd be better off implementing x402 instead (paying for access to a resource).

But then your end-user needs to already have a crypto wallet, understand what USDC is, and so on...another niche market.