Well, I just recently played a game where it ended up with a king and a rook vs. a king and a rook. He ended up winning by time. I just wanted to know Chess.com's opinion whether that position should of been a tie.

I am not chess.com (no one is - chess.com is a website not a person) but I don't believe there is any question as to whether his win is valid since time is a legitimate factor in competitive chess. You both agreed to the rules when you sat down to play and that was the fair result.

The only area for debate is whether it was poor sportsmanship on your opponents part not to offer you a draw.

I believe OP was referring to chess.com as a community.

On the question of the fairness of the win, if your opponent won on time fairly, you have no room for argument. As thefox31 said, the only point for debate would be poor sportsmanship. This is all assuming there wasn't a fault in counting material, judging or something else? Then you would have something substantial to argue about.

As long as there is sufficient mating material its not a draw unless agreed upon.  If you ran out of time then its a loss.

 No, because its possible to get skewered or just drop the rook itself, theres always alot of possibilities so you will have to play until the end or until someone agrees to draw.

Rook+King vs Rook+King is definitley drawn unless the rook can be immediately won. As long as you don't allow skewers or hang the rook, it's an easy draw and it's a little stubborn to play that out.

This is why I hate the clock in Chess. It's only there to regulate the length of time it takes to complete a tournament game. I think it's one of the reasons some people look at Chess as a 'sport'.  Without time pressure you 2 guys would have probably have shook hands on draw, the position isn't drawn but had you offered me a draw in that position I'd have said yes and then we could have started a new game. 

But keep in mind that one person used more time than the other. It's as if showing that the player who didn't run out of time didn't need to think as much to get to a position as good as the drawn position. In fact the person who took more time had an advantage in the game until it came down to who is going to run out. However this situation where either side can make their moves very quickly and draw easily is why I don't like to play with no increment. If you can not lose moving once a second, I think you deserve a good result and not lose on time but with no increment you'll eventually lose. Or say in a 5 0 game for example, both sides are in time pressure, he has 20 sec and you have 10. So you're only behind 10 sec but with no extra time this means you're pretty much going to lose unless you somehow get a cheap checkmate which is very unlikely.