The reason I don't think eBay is a good place for illicit sales is that it keeps open records of final selling prices. You can search for completed listings to see the sales price history of anything. If you were selling anything shady, you want to keep your plausible deniability open and say, oops, that was an error, or that's just us keeping a listing online so it wouldn't get deleted. If you sell a ridiculous thing for a ridiculous price on eBay, however, the completed listing shows the price that was paid for any product sold by any seller. Other platforms don't reveal this, so the shady deals will not be on eBay for this reason.
The reason I don't think eBay is a good place for illicit sales is that it keeps open records of final selling prices. You can search for completed listings to see the sales price history of anything. If you were selling anything shady, you want to keep your plausible deniability open and say, oops, that was an error, or that's just us keeping a listing online so it wouldn't get deleted. If you sell a ridiculous thing for a ridiculous price on eBay, however, the completed listing shows the price that was paid for any product sold by any seller. Other platforms don't reveal this, so the shady deals will not be on eBay for this reason.