I'm not arguing for Chrome's implementation. I'm saying we should do the more useful but harder thing of just not using "www" as a thing in browser URLs. They have correctly identified it as redundant, but instead tried to fix it by being too clever.

As I mention elsewhere, the first two are bad examples. (In fact. ntppool.org and www.ntppool.org are the same thing.) The third is a hack from the era where responsive design, browser sniffing, and polyfills didn't exist. It should probably die too, but doesn't have to here. The m.tumblr.com name is distinct from tumblr.com and is of the form I think better. Note that they didn't use www.m.tumblr.com.