This is pointless. It's impossible to create two pages that link to each other, for one. Also, as noted, most browsers won't allow URLs greater than 2k in size.
Nonetheless, it's tricky because you have no idea if proxies in the middle will be able to cope, mobile clients, and all sorts of things.. so you're right in the sense that it's pointless (if you want it to be universally acceptable ;-)).
I found that my web server started throwing 413s after only about ~30k characters.