Well, being a lowly crypto nerd without the resources to either backdoor or subpoena the top three server providers for masternodes, unfortunately you are correct. However, the word "anonymous" does not come with the stipulation that you must be a lowly crypto nerd without those resources, it means untraceable. Considering the fact that the majority of masternodes are being run with unmixed coins, sending subpoenas to just a few server providers and perhaps backdooring a few other ones would paint a rather clear picture of a large number of individuals who are involved in this project (i.e. the ones who are mixing). Get your hands on that info, create db of all transactions related to those address.. and you start to have quite a bit of the people "mixing" exposed, which in some cases would completely expose your "mixing attempt" and in other cases just eliminate possiblities, identify new parties, narrowing down possiblities. Let a guv bot run through all that info and the word "anonymous" is not much of a proper fit.

* Throw in subpoenas to 3 or 4 US internet providers (bc you all set up your MNs all over the globe but almost all of you live in the US) as well as timing attacks.... that's all without owning any any coins. Throw in 17 nodes trying to mix and acting as sybil....

Masternodes were live and being paid before mixing was particularly functional on any level. From when there were 40mns to about 1000mns mixing was pretty much unusable, and almost everyone used Amazon AWS, for which you must provide your identity.