> It is really worth it for Amazon to have them? I struggle to see how.
I think the main reason is that it gives Amazon huge amounts of market data essentially for free. For example, they can easily identify best-selling new products even if they're not sold directly by Amazon. If you're successful selling stuff on Amazon, it's only a matter of time until Amazon will compete with you and possibly destroy your business.
> If you're successful selling stuff on Amazon, it's only a matter of time until Amazon will compete with you and possibly destroy your business.
Mind you that this is not just a "when Amazon turns bad" scenario, but actually what they are doing daily. When I was writing software for Amazon sellers, their most profitable items were always some new niche product they discovered and worked well for ~1 month until Amazon swooped in and sold the same thing.
I think the main reason is that it gives Amazon huge amounts of market data essentially for free. For example, they can easily identify best-selling new products even if they're not sold directly by Amazon. If you're successful selling stuff on Amazon, it's only a matter of time until Amazon will compete with you and possibly destroy your business.