I recently got into DOTA2 after trying it a few times over the last few years. Things finally clicked for me around the time 7.0 came out.
I 100% agree that new players should not choose a support class. But for completely different reasons.
Support is a high level role. You need to be able to assess the flow of the match as it is happening, read the map and the action on the screen, and react accordingly. It is not a beginner role. The rest of the team will rely on you for vision / wards, and healing, and actual hero support within team battles.
What I've noticed (and have been guilty of in the past) is that new people approach a MOBA like a FPS and think that playing a 'support' will be easy because they can just spam heal their teammates like in a shooter. It does not function like that. At all. There is no TF2 Medic equivalent.
A good Support player can carry a mediocre team to victory. But a good team with a mediocre Support will always fail.
Seriously, if you're new and want to play a Support - don't.
Yeah, it's on my to-do list now too, terrible as I am at fighting games. Quite enjoyed watching it at EVO and the WC last night.
A little under 5 years, since Microsoft purchased Skype.