[ldjb]

Nobody is suggesting the user should be forced to type in the protocol, the subdomain, or the port number. If the user types in:

apple.com

It should lead to where the user wants to go.

However, there are good reasons for using the www subdomain as the canonical URL, and it is also worth noting that some users will habitually type in www anyway.

If you don't want to include the subdomain in marketing material, then there's nothing stopping you from leaving it out, just as there's nothing stopping you from leaving out the protocol.

[dalore]

And even just typing:

apple

Should lead to where they want to go.

[rootkea]

Which leads to 127.0.53.53 on Iceweasel 38.5.0 https://www.icann.org/namecollision