I think much the same dynamic is in play in the average developer's career. Think of all the job postings you've seen asking for 5 years experience in language

I think much the same dynamic is in play in the average developer's career. Think of all the job postings you've seen asking for 5 years experience in language X and 10 years experience in platform Y. Employers seem to want ever more specialization out of their developers, which for the most part is exactly the opposite of what is in the developer's own best interests. What developer wants to end up wedded to a single platform or language - if they're smart, or even just ambitious, they'll know that technical knowledge has a frightfully short shelf life. Not to mention that the only way to get a promotion or raise as a developer is typically to jump ship and go somewhere else. So it seems to be in their own best interests to branch out and try new things, which typically involves going elsewhere. In the software industry, at least, employers by and large feel little if any obligation to give their developers a career path, and that's why most developers move around so much. Not that I don't understand the employer's motives as well - especially in a field as in demand as development can be, why should they feel an obligation to give us a career path when we can essentially write our own ticket if we choose to? Don't feel any obligation to give your employees a career path, then - but don't expect them to stick around either. And no, it's not because they're lazy or spoiled or entitled or disloyal - it's a simple matter of economic incentives.