It is possible for someone to fly and someone to bomb. I did it with a friend on an empty server i created and it was alot of fun. I was the pilot and found it massively difficult to keep the plane stable enough but i imagine some people here would have no trouble at all. We got there in the end though and every worked great.
Problem is alot of people don't have a friend who likes to fly bombers with them and horizontal stabalisers let them do it alone.
If you do have a friend who likes that kind of thing though, even if they add stabalisers i'd recommend giving it a go with two people, just be prepared to strain your friendship
