Margins on eCommerce businesses can be an issue, while you might save on fees versus credit card fees and banking the business has to deal with managing that capital versus their fiat cash flow and liabilities

Then there's dealing with refunds, handling taxes, and managing custody do you do it yourself or use a 3rd party provider

For some I've spoken to it is just not worth the headache, they have enough work on their plate running their business, and for the most part fiat payments works and is already enough of a pain to manage

It's why I think consulting, freelance, info, and software products go Bitcoin early the margins are higher, and you can afford to handle drawdowns, if you're making 3-5% on a sale isn't much.

If I were to look at physical products i'd say tobacco and alcohol also have decent margins that wouldn't be too disruptive to manage on a Bitcoin standard right now.