Your not missing anything. Its been an ongoing problem for yrs. Most of those members are under 25 yrs old and they can't accept a loss as easy as they accept a win. Wait out the clock.
A question of etiquette

When you go into a game, say 10 min, for example. You need to commit to the entire 20 minutes. I have played opponents and myself included, on both Live and Daily who play their game and still run out of time. So, just wait out the clock and take the win. Yes, its frustrating but your playing a winning hand.
Primarily here because you spelled etiquette right!
Bad manners are the norm on this site. Just open another browser window, read or watch something while you wait for the inevitable.
put your settings to "allow multiple games"

I see this as poor etiquette, but this is still common. In fact, this is one huge reason that I play blitz. I usually play 10 minute blitz because I have plenty of time to think, but I have a short wait if my opponent just abandons the game. The drawback is of course poor connection causing some losses, but with 10 minutes I still may have time to refresh the page without getting disconnected.
Although I have sometimes lost games due to connection, I also have "saves". My favorite was a game I was playing where I had mate in 3 calculated, but then my connection went out ; chess.com gives 1 minute from this time to reconnect (not always so simple). I immediately attempted to refresh/get it back. I frantically attempted to click the pieces to move, but to no avail. When the page finally refeshed, I quickly moved my Bishop across the board to the square I intended a minute ago (I moved it so fast, I do not even know how I reached that square). Then I saw the time taken on the move to see how long it took and chess.com said 59.9 seconds! I won the game as calculated after that, but on that move I was 0.1 seconds away from being disconnected, and lossing. Obviously, I accepted the win, but realizing the poor connection quit chess.com for the day. Next time I logged in, my connection was fine.
The purpose of this short story is pure entertainment, but it is a true story that actually happened to me a few months ago. Regarding this forum, you may consider playing with shorter time controls. Your opponent abandoning the game will be less common, but other subtleties will come with it (such as connection, or thinking faster). Hope this helps.
Often I run across the situation when playing live opponents, where when my opponent is losing, bored, frustrated or whatever, instead of resigning, they just abandon the game, leaving me to either wait out the clock or forfeit an earned victory. Is this considered bad chess etiquette, or am I missing something here?