From my cynical experience it's a way to "reward" individual contributors with a meaningless title to make them feel like they are advancing their careers. It's purely responsibility without empowerment. In my naive days I was told I was a "tech lead" and I was very proud until I realized this meant being a scape goat for project's misfortunes without having the ability to schedule other people's time and thus materially change the way things as opposed to being the midnight oil superhero. Since then I never accepted such nonsense.

Make me a proper leader with the ability to truly delegate and alter scope, workload and the timing of work or pound sand.