Most companies organize technology around tools because the people making the decisions about technology at the highest level often don't really get technology; even CIO/CTOs are often from a tech-focussed business management background, not a strong engineering background with management skills layered on top.
You see the opposite at some places. Google, for instance, will generall yhave listings that mention a desire for "experience with" (or sometimes "significant experience with") some specific set of technologies but rarely specific years of experience with particular technologies, but also ask for X years of general experience in the field and/or a specific degree level.
Google appears (from their listings) to prefer to hire generalists with some experience in the the area of immediate need, whereas most companies frame their listings to focus on specialists without much emphasis on breadth.