Thanks for your feedback. The ad is designed to show a single short ad only after a certain amount of browsing activity. Once completed, you won't see it again for another 24 hours. The cross-device issue you mentioned is a technical limitation, currently, there is no option to sync this accross devices, but we'll look into improving that.
I think there has been a misconfiguration on our end causing you to see the ad immediately on the first visit. That's not how it's supposed to work, and it should be fixed now. If you're still seeing it too early, please let us know.
We're not trying to make the site frustrating to use, quite the opposite, but we have to find the right balance between hosting free content and operational viability. Feedback like this is exactly how we find the right balance. At the moment, we believe that one short ad a day to keep everything free seems like a fair trade, as long as it does not disrupt the browsing experience as you described.
Thank you again for being honest about your experience.