That's definitely a legitimate fear, as seen with the AOL controversy [1], but if they're just collecting aggregate statistics it's much less of a risk. I.e.
User ANON-123 with default font x and locale y and screen resolution z installed package x1
Is clearly a big hazard, but statistics on what fonts, locales, and resolutions have is not really. Even combinations to answer questions like "what screen resolutions and fonts are most used in $locale?" should be safe as long as the entropy is kept low. It is less useful, since you have to decide on your queries a priori rather than being able to do arbitrary queries on historical data, but ethics and safety > convenience
Combine ANON-123 with information from their browser, which has default font x, locale y, screen resolution Z, and package x1, and that anonymous data just became much more rich.
It doesn't take very many bits of information to deanonymize someone once you start combining databases.
[1] https://en.wikipedia.org/wiki/AOL_search_log_release