Interesting post, thanks to Tomcat to get it up 🙂.
I guess problem with popular platforms/websites is... people ! There is mostly two kind of people on this Earth: "builders" and "destroyers", can be seen as positive & negative, Yin & Yang, some create thing, see good things, feel good, act well, push other up, others are just bitter, lazy, have achieve nothing, have no dream or passion, they just like to destroy what others built, drag others down with them, it may probably make them feel less lame as they are. We see those two opposite forces fighting together everyday everywhere.
It reminds me Populous series from Bullfrog. Quite an awesome game design, anyone who don't know about these games could (should ?) play Populous 2 which was released on many platforms and can be played with WinUAE & Dosbox for instance.
To get back to the topic, making money is not that easy and sometime, some creator get lucky, but it doesn't last forever, I've read Candy Crush's author make a lot's of money for a while (about 50K$ a day), then the best game of the day become shadowed by another which is trending and so on. And the market is also very tough and players unforgiving. Anyway, whatever we could do, there will always be fans & non-fans.
Finally, 30% as fee may not be as an excess as it look considering all the costs of making a distributing platform avail 24/7, secure, safe with payments, etc try to set up on of these and gather enough traffic to get self sustained, I bet you'll like to pay "only" 30% !