Not sure you understand what Alexa ranking is.

The lower the ranking the better. It is basically a ranking on how important the site is to the Internet. For example, Google is a ranking of 1, being the most important site on the Internet.

Also your numbers seem to be wrong, STEMGeeks is around 600-700K.

The problem is a lot of users don't use or post from these front ends, and the duplicate content issues makes it very difficult to rank a tribe site without a large user base.