Most of the time delivery problems have everything to do with the seller. The point is that the seller and the product should be separated in reviews of the product.

Sellers are the delivery companies' customer.

If there are a lot of delivery problems, it means the seller has chosen a poor delivery company which reflects poorly on them.

I don’t think that’s not necessarily true. I don’t know how it works now, but at one point I know that delivery companies like Postmates would take the end customer’s order, pay for it, pick it up, and deliver it, without the restaurant (necessarily) knowing that the courier wasn’t the actual end customer. In that case, clearly the bad delivery experience isn’t the restaurant’s responsibility, although at some point they might decide they need to take action to resolve the problem.