Full Stack versus specialization

Re: Careers and skill sets

Growing up, it was ingrained in me to be good at one thing.  Be good at something most people are not good at.  Be a specialist. Be an expert.

Now, the trendy thing to say is to be good at a variety of things, be good at a whole bunch of different things.  Be a jack of all trades.  The phrase “Full Stack” is going around.

Which one is it? Be great at one specific thing or be good at multiple things.

My take is to be great at a variety of things, but be exceptionally good at one thing!  Way to toe the line with your answer.