In 2015 I was an internal referral from a top Tableau executive and I also came from a major competitor with unique technology and consulting experience. I was well-qualified for the role but I tried to establish confidence without being presumptuous or arrogant during the interview process. I was excited about the elegant product and the company culture, but I'd been disappointed twice in the past by Tableau's hiring etiquette: first, in 2006 when HR didn't return several phone calls, and again in 2012 when a different employee referred me and I went through a couple interviews that lead to a dead-end of silence from HR. (In 2012 the interview cycle was appearing to go well but Tableau HR went silent mid-way through my interview round, and didn't respond to my emails until I complained my internal referral contact. However, by that point, I was deflated by a few unprofessional snafus that had occurred during the interview cycle, such as the recruiter not sending the hiring manager a dashboard I'd spent a few hours building at HR's request, so I declined to pursue further interview as I felt the people involved were operating insincerely.)
Fast forward to 2015 and I decided to try again with the referral of a different employee, this time a top executive. I spoke to HR again, and a week later they put me in touch with a different hiring manager than I'd interviewed with in 2012. I had a one hour interview with her that seemed to go well. Just like in 2012, I was again promised a battery of 4-5 interviews including a product demo interview. Two weeks went by and I heard nothing from her, so I emailed HR. They promised to follow-up with the hiring manager. Another week went by with no further reply from HR. I emailed HR a second time but did not receive a reply. It was precisely the same etiquette shown to me before: interview; then empty promise of more interviews; then HR disregarding further contact.
It is hard to guess why they will spend their time and yours to host interviews (or have you spend time building dashboards) that seem to go well, but then they don't follow up on their promises or at least tell a candidate, "thanks, but no thanks." I would respect HR telling me they decided against me as a candidate, however, promising further interviews and then not replying to email or phone calls creates a negative impression of the company. I'd heard from two former colleagues that they both experienced similarly insincere interview processes. Candidates deserve to be treated more respectfully than this.