No one is spreading misinformation.
If you have a boosted car and youre about to launch it from a standing position, you can hold the throttle at a steady 4k, but you wouldnt build boost like you would if it was being held at 4K with 2 step. Thats all Im saying.
And yea, to get around this, you could just launch at a higher rpm to make up for the lack of boost when launching. Or you could also give it wot and start to launch whenever you reach the rpm/boost level which the conditions call for.
But either way, 2 step is the most effecient way to launch a boosted car IMO.