My code must conform to whatever programmatic interfaces that the exchange provides, even if they are not a good fit for the token's intended purpose. So yes, there is integration legwork that I the developer have to do.

> Using the network is not "skimming" transactions.

Sure it is. Users are paying a different token to miners (not me) to use my app's token. Tell me, if users are given the choice between transacting in both ETH and the ERC-20, or transacting only in an ERC-20, would they ever willingly do the former?

Your argument is: don't use the internet because electric utility providers are profiting off you.

Unlike electric utility companies and ISPs, users don't have a choice in the underlying blockchain.

This is more like Microsoft forcing people to pay for Windows when they buy a PC, even if they will install Linux.