>If the increase in seller fees is reflected in real pricepoints on eBay's market, it could work out as it really being the buyers paying the difference.
That would be true but that didn't happen. Final ebay auction values for stable items (e.g. books) did not rise by +7%. The sellers really did end up paying most of the fee increases.
Yes, some sellers tried to claw back the extra fee commission by adding extra "handling charges" to the total. That had limited effect because it made prices higher than (1) other ebay sellers that didn't add handling fees and (2) competitive Amazon Marketplace prices.
Also, Ebay lets bidders sort search results by "total price including shipping & handling" so adding handling fees just pushes your items down to the bottom of the list.