Never going to happen
Webmasters can't stop what they are doing long enough to organize because there is little they can practically do under the current iteration of the web. They do not control any part of the infrastructure where "power" resides and thus band together for collective bargaining.
ISPs have that potential (fortunately each is out for themselves, else there'd be no competition and rates would sky rocket for users!).
Search engines (see above).
Content creators such as News, Big Media, and Entertainment have that sewed up already (see above).
A webmaster union missed the train back in early advertising days, pre 2000. Associated publishers might have had a chance, but that would mean establishing publishing rules to be a member (not likely to happen).
We are left with a bunch of "billboards and farm barns" called websites and very few ever rise to the stature of being able to negotiate advertising deals of any mention.
At best we have the eagerness of users to click on search engines in expectation of finding what they queried. At the very best we have the top sites for those queries. Users have a reasonable expectation of privacy and also demand respect for their time and investment (their devices, their monthly fees). When websites do that, great. When a growing number of sites abuse those expectations the backlash is ad blocking.
Internally we know these things. Some have modified their practices and done well. Some do not care and have doubled down. Some are unwilling to change and make demands. These are personal choices and should be recognized as such.
Capitalism is a messy place. One can do well if the customer is satisfied. Or one can fail miserably. Sadly, the "economic basis" for all too many websites is being completely dependent upon third party advertising. The little guy is never going to win, might not even cover operating expenses, but the big sites cut their own deals with advertisers, even while running the third party servicing at the same time. Even the big sites can become abusive (many have) and ad blockers were the result ... with the small webmaster as collateral damage.
The little guy needs to find other revenue streams to survive. That's the real topic behind the ad block hysteria. Some can't change because there are no other options. Some won't change because they refuse to see the writing on the wall. Some fear change (rightly), and are locked into a wait and see.
Ad blockers are 10-22% (depending on your sources) and while that is a number, it is not a deal breaking number.
Take a deep breath and chill for a bit. Then put the thinking cap on and go from there.