Just to add, this is one of my favorite things about being a programmer. There's something incredibly satisfying to go from zero knowledge on a topic, to sufficient familiarity to program something about it, and then to drop it. Even better when you run into the same problem again years later and can magically solve it effortlessly.

In addition:

Small companies and tiny teams (like those building incremental software and contract projects) tend to prefer generalists. When there are 3 programmers on the team they each need to know and figure out how to do it all.

Larger companies with huge teams (like those building a AAA engine) tend to prefer specialists. When there are 150 programmers on the team, you can be picky to get someone who has lots of experience in a specific task.

Both types are needed. Even better for a person who has skills of a generalist and also a few specialties, these have more career opportunities available.