Significant amount of users that are multihomed have a setup that accepts defaults from two providers, and anounces their blocks to both upstreams. They receive no more information than the fact that their connection is up. No routing tables, no prefixes, just a quadzero.
The end user system is often nat'd, and run through a stateful firewall and all the information _they_ have is an ip address of the gateway via dhcp.
Any end-host updating solution must work through this gobbledegook.