Dota 2 custom games does support networking. However it hasn't been explored far yet. (see highscore on getdotastats.com, maybe faceit is using it as well)
I have no idea how exactly they are doing it but from lurking in their channel it certainly seems possible.
First we need ability to link Steam account with this site via Steam Login.
So you can sign up for a ladder on this website. And ingame when you are playing vs your opponent the result is automatically send here.
Many years ago there was a map generator on this site. You could make your own map by saying which tile is pathable, lava or ice. Also placing pillars. To apply the map into WC3 Warlock game you had to let the program write ~30 lines into the chat. That was not a user-friendly program but it was certainly awesome to play on your "own" map.
Maybe in future we can make our "own" map on this site, share and load them ingame via some simple commands.
This should be interesting in the future. Not now since every custom game is pretty alpha. This would give many players incentive to use this site. And if players can show their achievements they feel a lot more accomplished. E.g. data about their fireball hit rate in their last 20 games. How many games they have played and won. Also if you have won a ladder you can give the player a special title or warlock model all linked to their Steam ID.
Networking is for now largely untouched but it has potential. It is a bit early to discuss this but it should be kept in mind that it is possible. Many of these can be done manually (ladder) or by updating the custom game each time (title). But as the game grows it might be worth to implement networking.
What are your guys' thoughts?