using Tor is not loved by agencies. but if enough use the Tor Browser regularly (i.e. for complete mundane daily surfing) it is much harder to track down everyone.
forgot to add this: Tor traffic itself looks more or less like a generic TLS stream and is not easily detectable, but, as China and Iran are showing, it can be done. one layer more of protection/anonymity is to use bridges with different transport types hiding the traffic between the Tor browser and the entry node
