For generalists, assuming intelligence and a reasonable affinity for learning there is a heap of benefit. A generalist can become a specialist relatively quickly, especially when doing something day-to-day on a job. And often a generalist has benefit in understanding the big picture which aids in getting the job done.
Specialists have that edge in knowledge and often stay up to date better and general skills can erode quickly in areas of moving technology. This is useful when you need something worked on at the highest level right now and don't have learning runway.
Personally I've avoided specialising as I like the work diversity, plus enjoy the employment opportunity of having a wider skill set. Also in my field of marketing I find specialists rarely amaze me with their topic knowledge, sometimes the opposite. For some of the specialists I wonder if they get limited to specific areas as they dont like learning new things vs actually enjoying taking their knowledge to as far reaches as possible.