In theory black could play poorly and give the queen away by placing it next to the white king, then if the white king takes the black queen it would be a draw. Why would black do such a thing? Well playing poorly also means stalemating your opponent in an obviously winning position, which also happened here.
You can argue it's an "obvious win", just like I could argue if I'm a piece up it's an "obvious win" for me. But just because it's obvious doesn't mean the result is guaranteed to happen.
Also I guarantee you not everyone can actually checkmate a king with just a queen and king. So in fact it's not so obvious for a super beginner.
As for the benefits of the actual mechanism itself, in some positions you can actually force a draw or stalemate where you'd either otherwise be losing, or you are unclear of your advantage. For example in one of my games I was chasing the King around with my Rook where if the king took my rook, it would be stalemate, and if they didn't take my rook I would keep checking the king (while making sure the distance between my rook and their king is 0).
Well that's a fair argument. But I see it as a clever balancing rule.
Technically, if we get rid of the stalemate rule it makes the game harder for the defending (losing) side because it 1. removes an extra defensive resource and 2. forces the defending side to calculate an extra threat.
Now if we think about a theoretical perfect game, black always has a slight disadvantage due to going second. Therefore, in this theoretical game black would always be on the defending (losing) side. If we remove that extra defensive resource black has, which is a stalemate position then white gains an even bigger advantage against black before the game even starts. So in theory if one day chess is solved white might actually win every game.
Of course that's more of a conjecture on the extreme end but the point is that the stalemate rule is an extra defensive resource that aims to further the hopes of equality for black in my opinion.