Apple could make it happen. For some reason when an iPhone won't load something, people blame the thing instead of the phone. If they made Safari show an error page when a page used more than 256MB of RAM, suddenly the problem would disappear overnight.

No. Safari is already so buggy that it often crashes with the “a problem repeatedly occurred” message. That same message is shown when a webpage requests too much RAM. The problem did not disappear. People rightfully blame iPhone.