If you serve materially different content based on small differences, that's user-hostile, and common tools have no obligation to support you. Chrome shouldn't cater to sites that change behavior based on a www prefix, because the vast majority of users expect those sites to be the same. Hiding the prefix won't change their mind.
Small differences? A subdomain or an entire protocol is a small difference? And what about any web site that uses a "m." subdomain that doesn't intend it for mobile? I don't think that calling these things "small differences" is reasonable. And really, it makes perfect sense to not serve the same content over an insecure connection than over a secure one, but thankfully that change hasn't happened!
I agree, but Google doesn't just get rid of prefixes.
news.ycombinator.www.com would get normalized to news.ycombinator.com (not sure what would happen when using the www tld)
That's an extreme example, but there's an obvious security risk. This is a half assed change with buggy behaviour, regardless of whether you think www.domain.tld is materially different from domain.tld or not.
This should be the top comment. Users (including technical users) all behave weirdly by writing "www." depending on their mood or previous experiences. Developers setting up webpages do the same and often manage to screw up a CNAME on the www subdomain or to have two valid certificates for the www. And the non-www. Also, once you rotate cert you now have two to rotate. It's a mess and chrome's change is aiming at normalizing this. The complaints make zero sense.
So are https://example.com and http://example.com.
If you serve materially different content based on small differences, that's user-hostile, and common tools have no obligation to support you. Chrome shouldn't cater to sites that change behavior based on a www prefix, because the vast majority of users expect those sites to be the same. Hiding the prefix won't change their mind.