Shouldn't somebody resign at some point?

All things being equal, it's more likely to draw than resign.

Resigning is rude!!

Jeez, I'm so sorry to resurrect this topic, but, really?

I'm going to resign my next game in a tourney... Poor sportsmanship, I guess, right? 

There are no rules saying that one must resign at some point. If someone decides to play on, even though it might be a lost game for him, it is his choice. He might want to continue because he still enjoys the game or he is learning.

It is not our call to decide whether one resigns or not, just play the game... afterall that's why we are here right? To play chess?

In theory a given chess game should end in a draw.  In reality this only happens some of the time. An analysis of a game which ends in a checkmate will show a weak move or blunder, or multiples of such moves, which gives one side the advantage and if properly played out, the win.

Weak moves and blunders, however, can plague both sides of the board. So even though one side is in a weak position for a period of time there is usually a chance, however slim it may be, to  redeem the game. By resigning, one gives up on that possibility.

One move before checkmate.

You can only resign if the sum of the material on the board amounts to an even number of points, if there are more pieces left on dark squares than on white, or if your opponent is wearing a hat. Otherwise it is inded a horrendous "faux pas", likely to get one kicked out of any respectable OTB tournament. 

If you keep playing on, your opponet might make a mistake, then you can fight for a draw or you can win

Except on Tuesdays. 

Then Fizzbin rules apply.

Not resigning is rude!!