The author simple generalization of Bitcoin usage is mediocre. He jump in a conclusion without doing any research of his own topic. If he could have known how to type and search legal company that accept Bitcoin, he would be ashamed of what he just stated.
One major proof to refute the claim of the author about Bitcoin never been used for legal-transaction is the number of company that accept Bitcoin. Some of them are already listed on this article:
https://99bitcoins.com/bitcoin/who-accepts/ and many more unmentioned company and retail stores that accept BTC.
most companies that accept bitcoin do that just to be "cool". they convert the payment to real money straight away .
you can argue as much as you want , but paying with bitcoin is truly inconvenient .
cash is also inconvenient .
i prefer paying with my smartphone or a watch , this is the "new" way.