I guess, but somewhere between 1/4 and 1/2 of people already use ad blockers. It’s not a small segment of the population. Even more people use some sort of plugin.

I think it is more likely that certain sites require secure mode; just like today. I guess I could be wrong, and most sites will end up doing it. I still suspect there will be a work around; even if it is as complicated as a secure browser being run in a virtual machine and then AI removing the ads to show you the ‘clean’ version.

I am confused by why everyone thinks this is a big threat?

What stops the FOSS community from just continuing to allow ad blockers and other webpage editing features?