Listing on top-level exchanges costs huge fabulous money ... most projects don't have that much money. And many experts agree that listing on the top exchanges for millions of dollars does not justify itself from an economic point of view.
I think so too, that there is no sense to pay big money if the project itself has small scales.
Its just that you need to understand, even if you pay a lot of money for a good stock exchange, you may not have the result from it, because nobody knows about the project, you have to do everything gradually