Could website based crypto miners replace all internet ads?

If we ignore the "crypto is a scam", "crypto doesn't work", etc. questions and assume all good faith.

Could we replace all internet ads with on-site crypto miners that are working at low enough power to not hinder the user experience?

Since in today's world the majority of people are using computers that are way stronger then what they actually need or use.

And even you're on you're usually not doing anything CPU/GPU intensive except the website and video rendering.

Could such a solution to internet ads exist? Are there some obvious things In missing?

Or would this work for a year and we would have a nice time without ads until websites realise that adding ads doesn't affect the performance but does increase the profits and then we would end up having both on-site crypto miners and ads?

If it was functional we could also have "Donate by mining for X time/by mining until it reaches X money" buttons, which could help support open source stuff.

I guess the biggest question would be profitability.