Taking every piece

Why do some chess opponents take every piece on the board, even when they have the advantage? It's a bit irritating to see this when they could just go for checkmate instead. Isn't it unfair? I just feel like it's not necessary to take all the pieces. I don't get it and I've come across too many opponents who do that. Not only that, but it's frustrating because it's as if it's the only way they think they can win.

Some people do it because the other player doesn't resign.

I understand that, but there isn't much of a larger advantage if, say, the other player has 3 pawns, plus their king. When they do this, they normally haave a bishop or two/knight and one or two rooks. Isn't it better to just go for checkmate in that cirumstance instead?

Yeah, but if they figure they're going to lose anyways, whether it's resigning, shouldn't they just go for checkmate since it's faster?

Some do it as a punishment.

The person losing can end the game whenever they want by resigning.

The person winning can't. They're trapped in the stupid game, so they might as well make their win fun.

If I have enough pawns to get all my pieces back (two rooks, two knights, etc) then I do that and set them all on their original squares...

I never get to do this to anyone my rating because everyone resigns when they're really lost, but I get to do it in anonymous unrated games from time to time.

If you grab all the pieces, your oponent can no longer checkmate you, hence, if you run out of time you draw instead of losing.

Hey Hippy, how you doing? These folks seem to have missed your point, which was when an opponent has a win and decides to decimate you instead of coming in for the kill.  What can I say, brother? Some people are not very nice and we shouldn't invite them to dinner. The person winning can't end the game whenever they want? Sure they can; they can resign. And if they can't end the game, are they winning?

Don't worry about it, just stay away from the idiots. Like the ones here who couldn't grasp your simple point. Take care brother.

Could be worse, after taking all your pieces they could then promote all their remaining pawns to knights. 

My brother once got 7 queens on me, but we were just having fun.

That weasel, haha

If you're really bothred by it, why don't you resing and move on?

When I have a winning position, I look for the easiest  way to checkmate my opponent.  Usually, this requires removing some "clutter" from the board.

What ranking are you playing against? I usually clear the board and rook roll with queens and/or rooks if that material is available. Its easiest and makes it easier to avoid by mistake make it a draw by not leaving any legal moves to the opponent.

However, if the player is taking longer than needed to do this (for example danging around with pieces instead och check rolling you ) I understand its annoying.

Why you're not resign when you're down at material and your opponent keep making the gap larger by taking all your pieces?

I usually resign, but sometimes I don't because I want to see what I can do. Usually that's just with 3 pawns left on my side and they have 4-5 pawns plus the additional pieces. It's not like I'd have a chance of doing much with only 3 pawns and a king, which is why I think checkmating is better.

Lol I'm only ranked 900 or so in 5-minute blitz, so I'm not that good, but I usually play the same ranking as me. I've experienced a lot of delays/danging around too.