Spinal Elements interview questions

Phone screen with HR, followed by phone screen with Finance Director. Then a 5 person in-person interview on site. All of that is fine, no issues. BUT they started calling my references the NEXT day after the interview, and/or sending them really in-depth essay prompts before even making me an offer. All of this seems positive, but then they say they decided to promote someone internally. Cool, fine, the job description and culture left a bad taste in my mouth. But them wasting the time of my references seemed really unprofessional. Shouldn't you have considered that internal hire BEFORE that moment?

I was told to perform a phone screen then was assigned a design challenge project to create a tool that they sent me according to certain parameters. This interview was the first of 3-4 more interviews there would have been in the process.