It's possible, sure. I haven't been involved in the negotiation phase of any of the candidates so I couldn't tell you for sure how much back-and-forth there was. I can only tell you that the company I work for is very competitive here (think top 5 bay area companies.)

But when you see that it's literally Netflix's message that employees should go interview somewhere and bring in the offer to get their salary bumped, it starts making you not trust that the candidates are actually serious.

(Also I edited my comment after, but before I saw yours: We didn't just develop a theory about it, but there was a rumor that Netflix had this internal policy. I didn't believe it at first but here it is.)