I thought about this last night and wanted to make a (blog) post on the whole "comback" matter.
I think IceFrog was trying to eradicate the word "throw" from everyone's vocabulary
Think about it, how many times have you heard someone say "Oh x team threw that game so hard!" when they simply lost it. When people say someone "threw" a game, it's usually because that the team that threw had the victory seemingly set in stone before they "threw" it away. IceFrog aims to eliminate that feeling of victories being set in stone so quickly.
Obviously, early advantages STILL count, and count very heavily. However this change does not allow you to be careless with them. If your mentality is "We can dive this, and if they kill one of us, it doesn't matter, as long as we are taking those towers." then that is exactly what the frog is trying to get rid of. Gain an early advantage shouldn't mean "Okay, we can play a little more sloppy and still win since we did so well." It just means it's easier for you to seal the deal and win the game. There is no more "We can't possibly lose this now, all our carries are fat." They still have a fighting chance.
Is this different than the Dota we are used to? Aboslutely, but I also think it is for the better. Snowballing still exists, and always will, it just doesn't allow you to be careless.
That being said, I do think originally the numbers were a little high. Last night's patch may have been a step in the right direction, but at first glance, I agree with Milk that it may be too much. However that is a super hard call to make, as we really have to see it in a bunch of games before we can determine that.