succesful protocols are useful with only 1 end

just reading the iab's
What Makes For a Successful Protocol?
http://www.ietf.org/internet-drafts/draft-iab-protocol-success-03.txt
example 1: the first mobile phone was sold because you knew you could call any one of
600 million fixed fonrs from it (to think that last year in 12 months alone, more than
1 Billion cell phones were sold:)

example 2: www browsers could do ftp, gopher/ wais so you could get content immediately

example 3 skype - had voip but had PSTN call out capability from day 1, so you didnt
need another skype user to call

example 4: social nets - integrate web pages and youtube and mp3 sharing...

examples of doing it wrong -
noone used IPv6 coz the first code didnt do IPv4 intereworking from day 1.
noone uses sip as telephone people jumped on the sip bandwagon but didnt want to lose
business so noone did a sip client/proxy with skype style cal out

so all these things are complex....and call LOTS of stuff even when only 1 person deploys them

they all also breka postel's principle (badly) it seems to me...