It only guarantees reserves how about the condition of the product you cannot do that if it only guarantees supply there may be testimonials but we cannot guarantee that those testimonials are not fake, I like the present setup of doing escrow its safe and its a buyer and seller protection
Think using escrow would give the buyer unfair privileges over the seller. In my decades of experience buying and selling on the internet it is usually the buyers that tend to be the more problematic users of online marketplaces.