Sure, we are getting into semantics now. 15 years experience could mean knowing how to lead and bring up a team and product form scratch or it could also mean 15x 1 year experience if that person was constantly switching stacks/companies.

It's why we should compare salaries for positions rather than YoE.

> 15 years of experience might also mean they are excellent at PHP+jQuery but have never heard of Rails+React ;)

Not in this case. It is 15 years of proper software engineering and devops experience, for times in leading positions with additional responsibilities.