Guaranteed latency and packet loss between a home in the UK and a random link elsewhere in Europe or the USA is why leased lines exist and paying enough that people get a dedicated person to ensure their routing to peers is as good as it can be, i.e. think banker spending a fortune to be able to trade a ms or two faster than other people.
This is well beyond the realm of someone paying £20 per month to a consumer level ISP.
Peering can cost handsome amounts of money and while direct peering can be cheap, if you are heading to other countries then you build a complex pyramid.
Issue is that P2P gaming code will work nicely in a campus environment, but take it to the real world in any country and the difference can be significant. Hence why some firms still go the more expensive route of hosted servers that can at least be controlled more.