Top-level domains are still betraying the user's privacy. Does it bug me that PornoTube is significantly laggier on Firefox than YouTube? Sure. Do I want Mozilla to know that I'm visiting it? Hell no.
They wouldn't know that you are visiting it, just that someone is visiting it.
How can they not know that I'm visiting it? I mean, the data is coming from my IP address. Sure, they may be dropping that data before storage. But what if it's intercepted?
Connections to the Mozilla Telemetry server are done over HTTPS, so all an interceptor would know is that you are sending Telemetry and not what that Telemetry is.
OK, fair enough. Then an adversary inside Mozilla that can intercept the data. I mean, the NSA is inside Mozilla, right? It'd be foolish, in my opinion, to assume that they're not. Such a juicy target, and all.