I can understand why they are doing this. I think they should have a rating system like Amazon from 1 (poor) to 5 (excellent) and a comments section.
I think the problem is that sellers who don't like receiving negative feedback retaliate vindictively and that leads to misleading feedback.
A number of times I have paid for an item but the seller has not left feedback until I have left mine. That is very unfair because as a seller, if a buyer has paid, I always leave them feedback before they have received the goods.