[chrisco255]

If you create a "web3" website, it's up to you how decentralized you want that experience to be. You could have your content hosted on Filecoin, perform computation on ICP or Arweave, provide IPFS hashes to your users using open standards (HTML, JSON, Markdown, etc) with simple export functionality, open source code, ENS domain, etc.

If you take payments on your site via crypto, I'm not sure what you mean by "not accepting payments from criminals", as this is not a service provided by Visa or MasterCard either. I have a feeling running a criminal background check on all your users might impact your conversion rate, but you are as free to do that in Web3 as in Web2. (What are you selling that you would need to be concerned with such things anyways? If I'm selling an honest product or service, I don't care who buys it.)

There is no SLA. If you need an SLA you can create a hybrid site that both stores files in a central server and also backs them up to Filecoin or Arweave or Sia or Chia or whatever file network you like. But decentralization does tend to lend itself to resiliency, for example, Ethereum has 100% uptime over the past 6 years.