The eBay dispute system is quite good, similar to Aliexpress but possibly more refined (I didn't have to dispute anything on Aliexpress so far). I've had quite a few disputes on eBay and it was always fair, at some point they even took a £50 loss out of their own pocket because of an item that got lost in the post. I hope I never get to experience why people complain about
.
Paypal has a separate dispute system of their own, normally if it's an eBay transaction they would have you dispute it though eBay.
As for businesses selling on eBay you are partly right, some businesses do have enough in the bank to afford that but most don't, or at least not the eBay-type businesses we have now. Those that do afford it have most of their revenue from other channels and eBay is just a nice add-on.
Keep in mind there's also 10% eBay fees, 3-4% payment fees, 4-7% advertising fees, some listing fees, it all adds up. Locking a month's revenue is basically another 8.3% cost across the year and not many businesses can say they can afford to give away 8.3%. My employer luckily can afford that and we do some eBay business, but if they'd introduce that rule tomorrow we'd take down all the ebay listings and put the budget towards Google Ads bringing people to our website instead.