I fail to see how any but the third is web-specific. Any app with a server component will have scaling issues, at least there are well-developed mechanisms for spreading HTTP unlike a home-grown protocol. I've seen plenty of absolutely horrific native client UIs, and I'm looking at you Lotus. OS vendors and OEMs call the shots on native apps not to mention the nightmare of poking arbitrary holes in a firewall. And the last point is just a joke. There needs to be restriction on web access just as there is for applications. I can't install WoW on my work PC, why is facebook somehow different?