It intended by the developers. It has programmed rules and conditions. Thus, it can be neither a hack nor a cheat. Psyonix has even specifically pointed out that demos are not reportable offenses. Like any mechanic there is a right time to use it or at least specific situations it is more viable than others. As a player, we can make up rules for the game and expect other people to abide by them. You think demos are not the egit way to win? That fine, but be aware that no one else is bound by the restrictions you are imposing on yourself.
Early in the next season I put on my new Rocket League Trading and pulled of this play in a ranked 3 match. To me this play is the complete package: I pop the ball up and quickly get to the ground to drive ahead while my partner Kevlar goes up, I demo the goalie out of the air while Kevlar completes the inverted aerial. Hard to top in my mind.
The second one stands out just for uniqueness and the fact that I was able to deliver when challenged. There was some discussion on a Discord server about the possibility of a turtle demo. Someone was trying to get one but hadn抰 been able to. I was challenged to try it for myself and was able to quickly come back with a clip in LOLGA only my second game trying. I think the fact that I was able to line up a moving target made it a pretty impressive play despite it not really providing any value to my team.