Opponent ran out of time. How did this become a draw?

A common blitz strategy if you're going to lose on time in a winning position is at least try to make it a draw by capturing all your opponents pawns.
Ah, interesting, didn't know that either. Although, imho, the question shouldn't be if Black can _force_ a mate with K + B only, but if it is at all _possible_ that Black mates if White plays the dumbest moves ever.

Check out some of the other conversations that go into this in some detail: https://www.chess.com/forum/search?keyword=time+out+draw
https://www.chess.com/forum/view/general/what-is-quottime-out-vs-insufficient-materialquot has some detailed observations.

Ah, interesting, didn't know that either. Although, imho, the question shouldn't be if Black can _force_ a mate with K + B only, but if it is at all _possible_ that Black mates if White plays the dumbest moves ever.
Been trying to mate as black for fun with white making really dumb moves. It's hard. This is the only way I can think of to do it.
Christ, this is giving me headaches. How to prove that White can _avoid_ to be mated? You cannot just place K + K + B on an empty board, disregarding the actual position of Whites's pieces and pawns. Problem is : Engine won't help any, since not designed for this task.
I confess: Already had 4 cans, possibly confused.

Interestingly, the new FIDE rules state that as long as a checkmate is possible with the material left on the board (even if it's a ridiculous selfmate that would never happen) then it is a win.

Christ, this is giving me headaches. How to prove that White can _avoid_ to be mated? You cannot just place K + K + B on an empty board, disregarding the actual position of Whites's pieces and pawns. Problem is : Engine won't help any, since not designed for this task.
I confess: Already had 4 cans, possibly confused.
The way I figured it could happen, if white was trying to be mated that is, is to move all of his pieces to a square that the black king could just take them for free, all but a single pawn that promotes on a light square, promote to a bishop, move his king to a corner dark square and park there, then just shuffle his light squared bishop back and forth while black sets up the mate I've shown above.
Edit: I just wanted to try it for fun. It's an impossible mate to force.
I give up for today, need to get some sleep now - @all : Thanks a lot for your thoughts!
And, like always: Whenever you need a Leibniz medal laureate, there's no one around.
I think this should be a win for black. White could underpromote to a bishop, lose the rest of his pieces, and be mated as in diagram #5. The rules don't require the weaker side to be able to force mate; they just need enough material for mate to be possible by any combination of legal moves, which exists in OP's position. Note that when I say "rules", I'm referring to OTB rules and not chess.com rules

WOW. I knew something like this was possible. Each side with 1 bishop and 1 king. Although, the pawn could have been promoted to a knight and it was checkmate next move also.
The black king would be in check if white promoted to a knight on g8.

you won that game. complain to chess.com so they at least fix the bug. you can reference this article. https://www.chess.com/article/view/the-lonely-bishop-chekmate
I don't think it's a bug. I think chess.com knows that their rule about insufficient mating material is different from OTB rules, which they can do if they want

Interestingly, the new FIDE rules state that as long as a checkmate is possible with the material left on the board (even if it's a ridiculous selfmate that would never happen) then it is a win.
That's has been the FIDE rule for a long time. It just isn't trivial to program an algorithm to test that so the site uses a modified version of the USCF rules (the rule here differs in some cases from the USCF one) which only tests the material left by the player with time.