I've not used Vinted but is the SD on there much different? Nobody seems to complain apart from when people use a bad courier. If they are the same then surely its just change people dont like, you can see it on the many threads on here people saying I'll never use SD for this or that when this or that doesnt actually exist. 

With regards to eBay switching it to the seller pays, that would mean they have to drop the its free to sell and considering they jumped 2 feet with this line people will then cry eBay said ti was free to sell and now its not. Its all down to eBay chasing themselves with the promos that were once in a blue moon to every 2 weeks and sellers thinking meh I'll just wait for a promo and now its basically every day. 

I much simpler way would have been to have a single charge across all private and business accounts but give private accounts 50  (or whatever figure) of free per year as that would cover about 95% of sellers on here.