Why a one-man game and not a deathmatch?

Half-Life 2 singleplayer is of course a very nice story, the chapters are ok, we all love it but why don't we spend our time with other half life 2 fans or play together, not Half Life 2, we all love this game, the game engine (source engine) but why nobody plays multiplayer, there are very nice modes in it, we can play with different weapons, we can throw crowbars at each other (there really is), at least let's play deathmatch for the last time instead of sitting and waiting for Half Life 3 to come out because Half Life 3: Deathmatch is coming out (Half-Life 3 is coming out so that deathmatch can be done), let's have fun here for the last time.