I think that you are confusing "computer science" with "software development". It may be easy to get a Ph.D. in computer science and be poorly suited for work in the software development industry, but that's no more surprising than the fact that people can get Ph.D.'s in economics and be poorly suited for work in the finance industry.
Computer science is, obviously, related to software development, and in many cases its possible to take a CS degree that is focused on software development, but CS in general is not software development, and CS degrees in general are not vocational degrees in software development.
The best software developers may need to have extensive knowledge of CS, but merely having extensive knowledge of CS doesn't make you even a competent software developer.