Just because you can't fathom not being 100% ready to host 10 minutes before an invitation, if the responses here are any indication, most hosts/hostesses are still doing last minute prep at that time.
Being early is a MAJOR pet peeve of mine and from the looks of it, most people think it rude.
It is my belief that people who consistently try to arrive earlier than 5 minutes before the stated start time are just looking to "catch" their hosts unprepared and to subtly embarrass them. Must be a inferiority complex in the early birds that they have to make their host or hostess uncomfortable in order to feel good about themselves. They can pat themselves on the back that they are so superior because they are "always" prepared before a party. Not anybody here of course, but in real life.
I don't get it the thinking that if you are invited at 6:00 that 5:45 is ok. If the host or hostess wanted you at their house at 5:45, they would have put 5:45 on the invite.
So then why is ok to arrive at 6:15 or 6:30 if invite states 6PM

So it is ok to be late, but not early

If hostess wanted people to arrive late then early, then why not put dinner invite for 6:15 or 6:30??