Nah. AFK/Leaver penalty is not high enough. Every other match sees a leaver of some sort. Even being DC'd for one or 2 rounds can have huge impacts. It can be the difference between winning 13/12 or losing 11/13.
It can set the tone of the economy. Winning the first and second round can make it easier to win the rest of the rounds.
To you it is just being AFK for a round or two, but for your team mates it can the start to a rough match.
One thing to keep in mind, is that this is a F2P game, with nothing stopping you from creating a second account. If your connection is that bad, a sock account might not be too bad.,