Well, first off, this question only makes sense with respect to Human Geography, not cartographic or landform geography. It is a very, very complicated subject open to much interpretation, but generally speaking, it is about not generally speaking about anything in the social sciences - (that's a pun, by the way). Does that make sense? Probably not.
Traditionally, generalizations have been used to broadly explain mass social movements, class struggles and major changes in history. Not everyone has time to read a PhD thesis, and great forces still have to frequently be explained within a page or paragraph or two. Generalizations are a way to distill down complicated subjects for average person consumption. Now, everyone knows generalizations have all sorts of exceptions of course, but Post Modernists always bristle at broad-brush explanations. They are sticklers for detail and specificity and reject any effort at generally explaining complicated social subjects at all. This helps them get support for their own intellectual views or agenda, as you can use the post modernist view to explain any social action just about any way that you want. It's a way of throwing out any old rules, and replacing it with not much of any structure other than empathy and understanding. Post-modernism borrows heavily from Marxism and basically says your race, sex and culture dictates your view of everything, and hence no generalizations regarding anything are true. Things like the modern Woke movement, color-blind casting in television and movies, and Critical Race Theory (CRT) are all post-modernist concepts. If you can wade through it, take a look at chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://old.amu.ac.in/emp/studym/99999257.pdf if you'd like to learn more.
