The larger and more mature a company is, the more able it is to afford a job title which specializes in something narrower. It doesn't need to be super large; if the product is very technical, a specialist might be necessary.

The situation can be a bit different in a large company. They might want to hire a Java developer, or a front end developer. These are specialist roles, in that the people in them have chosen a professional specialism. They're commodity specialists though, so common that they're not thought of as special. It's more rare that they want someone who can do devops, UI, JS, RoR, Java and C++ - this is a generalist.