[notatoad]

serious answer: you don't. the idea that anybody should be able to sell to anybody else is fundamentally invalid. global-scale marketplaces are a bad idea, because as soon as money starts changing hands, then fraud becomes a risk and the sort of impersonal, evil-seeming anti-fraud actions that ebay takes become a necessity.

nobody has any inherent rights to selling on ebay. they do their analisys, and determine if you're a fraud risk worth taking on or not. and if they don't want to take on the risk of allowing you to use their platform, they ban you. just like they did to the OP here. it's not evil, it's just the only responsible behaviour for a global platform that allows anybody to sell anything to anybody else. Any other platform reaching eBay's scale will have to do the same thing.

Facebook marketplace can do a bit better, because facebook has an absolutely absurd amount of your personal information that they can mine to determine your fraud risk. Some other small-scale indie services can pretend to do better, but the only thing that allows them to do better is their small scale. Online classifieds like ebay's Kijiji subsidiary can do better because they don't handle the transaction, and you take on your own fraud risk and only deal in-person.

at some level, every service that does this has to answer the question of "how do we deal with fraud risk" and the answer to that always has to be forbidding some set of people from using the platform. better to do that by initially limiting the scope of the marketplace to something small, rather than kicking people out based on some criteria.

[caf]

Right. The root cause is that Internet is a Dark Ocean, and any honest little fish that pipes up saying it would like to buy or sell a used iPhone is likely to be swiftly eaten by a shark.

[ajb]

So, how do we scale the creation of small market places?

[notatoad]

again: just don't.

small communities of people who trust each other can sell things to each other without any VC-backed platforms getting involved. "scaling it" is the problem, but nobody needs that. all you need is a messageboard, either digital or a literal bulletin board. trying to force marketplaces to grow bigger causes problems.