Starting a business without capital, in my opinion, really doesn't make sense in a time where every business definitely uses capital, as you said, affiliate marketing, this still uses capital, where the capital we use is a quota and our brains think about how to get lots of affiliates.
Yep. I can agree if we don't always need a big capital to run a business. But I also disagree if it is possible to run a business with no capital at all. Everything requires capital, even we access this forum we need money to have an internet connection. Sure affiliate marketing needs capital, besides internet connection sometimes we need to have certain social media, too. Social media, money, and ability can be categorized as capital if it is based on our own definition.
So in my opinion, capital is not just money, but there are many supporting factors that can actually make the business run smoothly
Unfortunately, OP clearly described capital as money. So other factors can't be categorized as capital. However when we want to start a business, other factors also can't be separated and have big roles as well. Sure, to run a business smoothly, it doesn't only depends on good amount of money.