I recently sold a 35 year old camper van, with one click I shared it in a group for old cars. People who saw it in turn shared that again in other groups for cars.
Users see those listings in their feed, on the same page where they might see news or funny dog videos.
If I sell on my local version of Craigslist, only people who actively search for a camper van would see it.
My wife sells a lot of our old stuff on marketplace. It's quick and simple to do, and there is a huge market. It's all small stuff that no one will pay shipping for, but if you are local and can pop round it's absolutely fine. Things like kids toys, books, mostly low value stuff. We've got rid of knackered old furniture for free on there because it meant someone else would take it away.
It has the advantage of market size. A lot of people are still on FB for things other than marketplace, so it's an obvious place to look when you want to buy something second hand. It's also easy to share your listings on FB.
Facebook can put stuff in front of so many people.
I have sold furniture, electronics, used clothing, all sorts of crap.
They have cornered the market in auto and housing (including rentals) but are losing out on general goods. I know a lot of people who don’t even bother looking at TradeMe anymore to buy, let alone sell.
I can’t remember when I last logged into my TradeMe account.
So amazon is not that much popular here - the force of habit for buying on Allegro works against Bezos' company. They enter too late, offered not much at the start and often products descriptions were poorly machine translated. There was even a picture that ran for a while around our part of the Internet where some Nigerian economy book title due to this translation mishap become really offensive.
Seemingly, craigslist should allow for this as well. Unfortunately for craigslist, however, it has been societally labeled as “for the olds”
"No, I'm not going to accept 1% of what I listed. I'm going to put it in the garbage instead since my time is now worth more. In fact, I've now had enough of you assholes call and lowball me that I'm now net negative even at what I listed so into the trash it goes."
Presumably, Facebook Marketplace simply hasn't gone through the degradation cycle, yet.