Why do people here just say just move on and people do it?

I know - it is majorly irritating - people know that they SHOULD move on, and of course eventually they do - but in the meantime, those people need a helping hand, and are just coldly told to "move on". It's not helpful, and it's not "advice". It's a stupid, irresponsible thing to tell someone who is grieving and heartbroken. It's also a lazy answer.