The point of my comment was that, if [actor] is not using any pseudonym but is instead nameless, then there is almost no active way to pursue that actor, aside

The point of my comment was that, if [actor] is not using any pseudonym but is instead nameless, then there is almost no active way to pursue that actor, aside from its adversary running malware on every machine in the world and scanning the disk/memory for relevant data- and even then, the machine can be encrypted/wiped and airgapped. An action can be taken and then once completed, as long as it was properly anonymized on a technical level (easier) and social level (harder) against a given adversary, there is no more heat. The actor never needs to interface with anything related to their activity ever again in any way, and can only screw themselves if they deliberately tell people what they did. And even if a nameless actor does 1000 things and gets caught for only 1, because they had no name/common set of characteristics, those 1000 things cannot be tied together. They're just caught for the one thing. So opsec is hard... if you have a big huge ego or want to maintain some kind of central infrastructure.