I think maybe there is an assumption about what exactly was, or should have been, the first read.
While it's obviously true that if the left side is the first read (and if it's shallower, it may certainly be), that's really the only thing Dak could have done. Do we know, the right side wasn't supposed to be, or shouldn't have been, the first read?
I haven't looked at the pre-snap alignment all that much to even have an idea one way or the other.
The short side of the field with the TE closer set would logically be the first read (pending defensive alignment) to get the ball out quicker as your wideouts on the wide side would have to receive a longer throw. From Dak's perspective, at the :08 to :09 sec. mark prior to seeing Schoon's shoulders start to open this play looks like a gimme. A throwing lane is opening since Sweat is running wide and Tyron is set to move him wider, and Dak would have to anticipate Ferg running the proper route instead of politely splitting the defenders. Also, run the vid. slowly a note how quickly the pressure is coming from Dak's right making a throw to that side more challenging. The read wasn't the problem, the execution was.
Adding to Ferg's failed pick attempt was Blankenship's recognition of what was going down and getting out there to take down the easily tackled Schoonover (per Baldy). I'll leave it to you guys to debate if he got there too soon.
I can't even imagine the amount of complaining on here if Dak scanned the left side first, decided it was a no-go and then reset to look to his right only to take a sack or have his pass batted down since Pollard was apparently assigned to NOT (or was he?) pick up blitzers. Would have been a chorus of, "Schoon is open, why are you holding the ball again, Jesus?"
Bottom line is brain farts in execution continues to cost this team.