Why does eBay favor buyers? It's very simple, and if you don't grasp it I would suggest that you have learned very little for all your years in online retail:
Buyers are more valuable than sellers. That's why both Amazon and eBay have spent tremendous amounts of money "acquiring buyers." Amazon, in particular, justified the constant losses that it posted during its early years by arguing that it was "acquiring buyers." eBay did the same, but without spilling red ink as notoriously as Amazon.
Two things that I have learned in my two decades of selling on eBay (and elsewhere):
1) Each seller needs a substantial pool of buyers to support him or her. I know that I couldn't get by on only a handful of buyers. If I'm going to make money — and for eBay to make money off of me — eBay needs to keep a strong and steady stream of people checking out my listings. The higher the ratio of buyers to sellers, the better for eBay — and in the end, the better for sellers as well.
That means that eBay has to make sure that a whole lot of buyers feel comfortable buying here, and that means they're going to give the appearance of favoring buyers over sellers much of the time. Think about it: If you go back as far with eBay as you say, you should remember a time (as I do) when it wasn't uncommon to meet someone who said, "I would never shop on eBay because I don't want to get ripped off." It's much less common to hear that now, because of the Money Back Guarantee.
2) Related to my first point: eBay has lowered that barriers to entry to becoming a seller. Literally, anyone can do it. So there is bound to be an oversupply of sellers. We're all disposible. Like the Persian Immortals, if one of us falls, someone will step right up to take our place. eBay knows this; it knows that it always has too many sellers for the current buyer pool to support.
It also knows that attrition will get rid of the worst sellers, the ones that are simply not fit to be sellers in the first place.
