I stumbled across this article: https://thelibre.news/foss-infrastructure-is-under-attack-by-ai-companies/ There it's mentioned that they started to use something called Anubis that uses proof of work to prevent too many requests from being sent. That got me thinking. If instead of proof of work in your browser, the site requests micro payment via lightning, would that work? Would it be better then the current solution (some legit users report the proof pf work taking 10 or more minutes on their machines)?