I agree with you on this, and it really goes back to a series of decisions the Supreme Court made decades ago regarding these administrative agencies. Scalia once famously labelled the U.S. Sentencing Commission as sort of a "junior-varsity Congress" because it had been given authority that should be Congress' alone. You could google "Mistretta" (the name of that case) and read his entire entertaining rant on the subject.
In any case, I wasn't trying to open that can of worms here. I was simply trying to point out the legal power of the NLRB, and what it meant in this particular situation.
It seems to be a natural consequence of a bigger and more complex, centralized government. Eventually the growth expands beyond the boundaries of control of where the ultimate power theoretically exists in a representational government (the electorate). So you have these czars and agencies operating almost in a vacuum, insulated from the controls built into the system of checks and balances. When agencies like the NLRB start encroaching on Constitutionally-mandated authority of a legislative branch, it behooves of to point that out (not that it will necessarily make any difference).
The Obama Administration seems particularly roguish in this respect. There have been quite a few documented cases where the Executive has essentially told other branches like the Judicial and Legislative to basically shove it when it comes to implementing its agenda. I can't help but think if it were a Republican administration doing that the media and the legal academic community would be screaming bloody murder. But Odouchebag gets a pass, naturally.