Also what I don't like that enabling this feature disables page zoom. This is inconvenient because you have to choose between using zoom and fingerprint protection.
Actually I think that when zoom is less than 100% (i.e. the page is made smaller) it is possible to report to the page original window size rather than scaled up size. Many sites today use gigantic font sizes and they are difficult to read without zoom or high-DPI display.
> Also what I don't like that enabling this feature disables page zoom. This is inconvenient because you have to choose between using zoom and fingerprint protection.
I don't think it does disable page zoom; I have privacy.resistFingerprinting set to true and can still zoom just fine. (It does disable per-site zoom settings, but you can still zoom any site to whatever size you want each time you visit—which is certainly inconvenient, but, well, the state of the web is such that you can choose convenience or privacy; Firefox giving you that choice does not mean that the necessity of choosing is their fault.)
12px is not tiny. A bit small for body text considering the narrow font, but not unreadable. If you consider that text tiny then you should configure your browser (or OS) to enable DPI scaling (effectively zoom by default) instead of demanding all websites have giant text.
Actually I think that when zoom is less than 100% (i.e. the page is made smaller) it is possible to report to the page original window size rather than scaled up size. Many sites today use gigantic font sizes and they are difficult to read without zoom or high-DPI display.