Please cite any evidence you have for that. I've been citing a 2017 Supreme Court decision where what you've said is absolutely NOT true -- by a 7-2 margin in the NLRB case.
Remember -- You have to cite a case where a temporary appointment of a "principal officer" (as opposed to an "inferior officer") was upheld. I'll bet you can't find one.
I must admit that my info is based upon a legal analyst on a news show, I don’t recall which, stating that the act was upheld by the Supreme Court. Next time I am at my westlaw terminal, I will try to remember to check it.
The NLRB case is very distinguishable. That appointment was overturned because Obama misused the recess appointment power, if I remember correctly.