In what sense are sorting algorithms more fundamental than say font rendering algorithms? Nowadays, they are both supplied in standard libraries and few programmers would implement either.
They are used in many more situations. A lot of problems can be reduced[1] to or contain a sorting problem. The same cannot be said about font rendering algorithms.
You are right in the sense that there is no formal definition for what makes an algorithm fundamental (AFAIK - I am no expert on the matter). However, the general consensus seems to be that since a large number of problems make use of or can be reduced to a sorting problem, it is more fundamental than font rendering which solves exactly one problem. In fact, I wouldn't be surprised if font rendering algorithms use sorting in some way.
