Excluding a page is a manual process however, requiring to set the header mentioned in the blog post. So website owners have to explicitly opt-out of FLoC.
Not an Apple fanboy, but Safari is a great example of software which has changed its default behavior to prevent creepy things from happening.
Different companies, different incentives
I guess this topic is more of a political issue rather than an obvious compatiblity issue, so it's not as clear cut.
But adding special code to deal with buggy clients is something everyone has to do sooner or later.
Anyone who runs a site and wants to opt in against a default block should have to take extra action to reduce their visitors privacy, and should be called out for their behavior. As others have noted, there are already plenty of workarounds in use for many reasons... this is a BETTER reason than most.
And when that does happen, Google is famously transparent in its actions and easy to contact to resolve such issues.
(You may detect a little touch of sarcasm above!)
Is it way to cynical to think that coming from the worlds largest advertising company that can’t mean anything except “monetizable web content”...