You have to distinguish between the incentives for the company and individuals. For example, it makes little sense for a company to use a different web framewo

You have to distinguish between the incentives for the company and individuals. For example, it makes little sense for a company to use a different web framework every year. It makes sense for individual developers to accumulate a large list for their resume. Likewise, it makes not sense for a company to optimize for a large headcount. It does make sense for an individual manager because leading 100 people looks better than 20 on his resume.