This entire statement is why you're bad at TF2.
Short of an uber, running directly at ANYONE is a hilarious bad idea. Every single class in the game has at least one weapon designed to discourage that sort of play, assuming the player has even a modicum of accuracy.
Here's a list of other reasons why w+m1 is basically idiotic
1. Holding W while rocket jumping/nade jumping/etc is actually detrimental to air control.
2. Pyro flames have less reach when running directly forward, and makes it very easy to fire projectiles in a non-reflectable way.
3. Classes that should otherwise absolutely get wrecked can instead kill you. Medic needles, spy revolver, engineer/scout pistol, sniper smg, all do amazingly well against someone running directly at you.
4. If you're W+M1'ing, it usually means you're not taking any advantage of the environment, which is awful considering TF2 is all about height. Any opportunity by any class to get above the other team is usually taken and abused. You won't just die, you'll die without ever landing a single shot.
But I'm sure it works well in those scrublord games you play.