Most of the posts that are frequently featured in the homepage are about social problems or styles of life common to that country (or most first world countries), and even limit to only United-Statesian media discussion. They do not appeal to someone like me, who has different thoughts, different people, different problems. It’s hard to find something relatable in (most) non-local communities, because it’s just about this style of culture. It doesn’t helps with the poor website discorverability, making me limited to these same repetitive and unfunny posts.
There are 330,000,000 million of us and we all have internet. More populous countries, like India and China, have languages and alphabets so far removed from English that the vast majority of us can’t begin to read them.
So yeah, I would expect American posts to dominate most of the Western world’s online activity.
citation needed ;)