Ask HN: How to get a job after you have been a CTO?

Hoping some of you can give some me some insight into my situation. I am currently a CTO looking to get back into an individual technical contributor role. I had 7 years of technical experience as a programmer and unix admin. Then I got a chance to work as a project manager where I was quickly promoted to VP Technical Operations and then Chief Technology Officer for the last 3 years. As CTO I recruited a team of around 10 developers and lead product development for company with around 200 employees. We were very successful and the company is being sold. I have recently applied for systems administration, product manager, project management, and developer positions at larger companies and have been told that I am not a good fit for those roles by the HR recruiters. Is it true that someone is no longer a good fit in an individual contributor role once they have moved into C-level management? If so, why?