Sins players bashing every new guy is a myth
go online and get destroyed a few times...
Big difference between bashing and getting destroyed.
..start copying peoples moves.
Yes, replays are the key to accelerating your learning curve. Not only will you see flawed tactics succumb to superior micro-mgmt skillz, you can dissect build orders and upgrade ramps. Also, if you watch a replay with a good eco player, notice their progression of research trees, and corresponding transition to military later in game.