It's similar to when you use Linux or an obscure privacy-preserving browser. You've made yourself way more unique just by doing that.
(I'm not sure how the math works out though, vs. actually running all that nasty tracking stuff.)
But, yeah, anti-fingerprinting is still a useful signal if less people do it. So more people should do it; especially if they're less likely to be targeted.
"More haystack" makes their job harder.
for example, a constitutional representative in my country attempted to place restrictions on unfettered gambling advertisements. a single day later, photos emerged of that politician having dressed as a nazi for a costume party in his youth. that politician stood up for what was right and then got fired for it, by losing his job and his status in the court of public opinion, effectively achieving no change.
exacting change isnt always such a simple process as embodying the end result.