Is there anything these preferences disable that isn't disabled by unchecking the three boxes (telemetry, experiments, crash reports) in the regular Privacy & Security tab of the Firefox preferences?
FF has a default link that it checks for capture portals on wifi networks. I think that it must be turned on all the time, though something in the about: pages might turn it off.
Tho that isn't mentioned in the article, and I'd be surprised if mozilla collects any data there (other than something like a hit count).
Of course, there are also the update checks, both for Firefox itself and extensions (both not mentioned in the article either, and probably a bad idea to disable this functionality unless some external source like a package manager does the updating for you).