Ask HN: Is it reasonable to be a generalist programmer for your entire career?

I'm curious about this for my own personal reasons. I currently am working with 10 years of experience, graduated a little later than other students at 26 and that was when I started my career. I consider myself to be more or less a generalist with no extreme pros or cons. But, with 10 years of experience a lot of places consider my lack of expert knowledge in any particular area to be a con.

I failed Triplebyte's phone screen/code tests twice- this year and last year. While they are not the ultimate test of skill they do provide good detailed feedback. Generally speaking I've been told that I know a little about many different topics but can't go deep into one.

But maybe it's for the best if I can't become an expert in something. Is it reasonable to continue my rest of my career as a generalist programmer and maintain employment? I am now a bit closer to 40 years of age than 30 and at this point I still cannot find an area in programming that I can consider myself good enough to specialize in and become an expert.