It is absolutely false. I've seen Goff go through 3 to 5 progressions on a single play more than a few times this year with my own two eyes. Hell, I'll quote Sean McVay on this:
"He got all the way through the progression and found Todd on the backside," McVay said of Goff. "It was basically his fifth read. That's impressive."
Here's the play he's talking about:
View: http://www.nfl.com/videos/nfl-game-highlights/0ap3000000849065/Gurley-keeps-his-feet-moving-breaks-tackle-for-27-yards
We're not running a two-read offense. Hell, that doesn't even make sense. Gurley wouldn't be having the year he's having if we were running a two-read offense because he wouldn't be one of the two reads. McVay loves to attack all three levels of the field. If he were running a two-read offense, Goff would be reading deep to intermediate. Instead, Gurley catches a lot of passes when Goff checks down after looking down the field.
This isn't a two-read scheme. Goff is reading the entirety of the field and going through the same types of progressions as the Pro Bowl and All Pro QBs.
And they run the two and three WR bunch sets because it makes it difficult for the defense to press the WRs, causes confusion, creates early separation, and allows for us to utilize pick routes. Crosses and slants are known for being man-beaters. That's why we run them so often.