[cks]

My point is that having pet projects might actually increase software development skills. In the same way that practicing any activity generally makes you better at it. People who're good at socializing, basketball, football or whatever typically invests time in it. The more you do it the better you get at it. Why shouldn't the same apply to software development?

A person who invest their free time in relationships or sports will probably get better at those things than a person who only invests in pet projects, but why shouldn't the person investing in pet projects get better at his/her activity?

I think it's unfair to say that the employer should ignore all skills achieved your in spare time because other people choose to spend their time differently.