Reconstruct interview questions

Applied online and got a call from the CEO the same day to set up an interview. Interview went well and the CEO told me he was going to discuss next steps with the CS manager and he asked me to follow up in 48 hours if I hadn't heard anything. I did as instructed and gave the CEO a call 48 hours after the interview. CEO told me that I had been eliminated as a candidate because I did not send an email after the initial interview thanking him for his time. This would have been an acceptable viewpoint in the 1970s but unreal in 2024. Very egotistical and not a CEO that I would want to work under.

Drawn out and a bit of a time commitment. 30 minute phone call with the hiring manager. If you make it past that, 3 separate 45 minute long interviews with 3 seemingly random higher up people in the company. They were friendly and easy to speak with, it just felt unorganized.