One Mozilla developer claimed that explaining PPA would be too challenging

It's not that difficult to explain. "When you visit the website of a participating advertiser whose ads you've seen, do you want us to tell them that someone saw their ads and visited their site, without telling them it was you? Y/N"

But if they asked such a question almost all of the small fraction of users who bother to read the whole sentence would still see no good reason to want to participate. Coming up with one is that hard part. It requires some pretty fancy rationalizations. Firefox keeping track of which ads I've seen? No, thanks.

If there was an option to make sure that advertisers whose ads I've blocked know that they got blocked, I might go for that.

The writer apparently thinks that the previous Mozilla misstep into advertising land was the Mr. Robot thing six years ago, which seems to confirm my impression that this one is getting a bigger reaction than their other recent moves in this direction. We'll see if the rest of the tech press picks it up. Maybe one day when the cumulative loss of users shows up more clearly in the telemetry they'll reconsider.