Thinking of making one, would it work?
No. To have any sort of escrow you need to have trust.
If you create a site solely for escrows to offer their service and match up buyers with each other then you can probably imagine the chaos that scammers will create. How will you make sure that these escrowers are legit but not duds? Plus how will you make sure that they pay you a cut after each transaction?
Unless YOU want to be the escrow. In that case, why would anyone trust you? What's so good about your service that makes nobody want to trust a more seasoned operation like LBC or paxful?
Not a good idea at all, you'll get criticized all round, nobody will trust you, and you'll spend a ton of money you won't be able to make back on devs, graphics, customer support, server costs etc.