On every single release they add new hidden options regarding tracking by mozilla (see Normandy and shield for example, which you have to go to about:config to disable).
In addition to that about:addons uses google analitics and does not allow for it to be blocked by extensions, plus mozilla sites use tracking scripts (googletagmanager etc) that need modifications in about:config to be blocked (extensions.webextensions.restrictedDomains).
Finally mozilla does not seem to be taking any measures to make firefox more resilient to tracking - in fact they support more and more technologies that diminish it. (web fonts, webgl, geolocation, user agent mentioning the version language and OS, etc)
Edit: Sorry, by "web fonts" I meant the ability for sites to read the fonts that you have installed. I do not know if actual web fonts can be used for tracking.