Among wikidot.com features you still list:

"If you want, you can start earning money with Google AdSense whenever someone clicks ads on your pages. The best thing is that you can set if the ads are displayed to everyone or only to unlogged Wikidot users. You also have control over placement, colors, sizes — and you can start now!"

The page you link to ( https://www.wikidot.com/adsense ) doesn't exist anymore but for many years already Google is asking us to add an ads.txt, to avoid losing income.

To me it seems like a basic feature. If it is impossible to implement it, kindly let us know and adjust the list of features.

For more details, see: http://community.wikidot.com/forum/t-10807863/google-adsense-asks-to-add-my-id-to-wikidot-com-ads-txt#post-4200060