What would an ideal discussion space look like to you? I happen to agree with the idea behind your post, namely that Americans can be frustrating sometimes. However, if you build a website around different core values, then Americans will complain that they can't get any headway or discuss things they care about. You will have merely shifted the environment to one that is favorable to you. If you create a website with balanced demographics, discussions will merely shift into various safe-spaces for each ideology. It's inevitable.

The main paradox in your view is that you see Americans as being fixated on their own values while not realizing that you are doing this as well.

Therefore, if the problem you experience is that you have a negative prejudice towards commenters, or are unable to "think seriously" because of the core difference in outlook, the only reasonable solution is that you change your attitude since the site's demographics will not change barring a global cataclysm.

I'm also a bit surprised by the notion of all non-American Western nations having essentially the same views. Despite some resemblances, important differences lurk beneath the surface, not least within the countries themselves.