While their answers are low quality, and in some cases are outright plagiarism, there is no direct evidence that they are anything but a legitimate user trying to help other users.
If you suspect that there is something untoward in an account that may be being set up to post spam then please flag one of their answers for moderator attention and explain your concerns. A moderator will investigate and take any action necessary.
Otherwise simply use the standard flags which will either push the post into a review queue for the community at large to deal with on a per-post basis. "Very low quality" is the obvious flag here, and would put the posts into the low quality review queue and also in front of moderators.
Lots of downvoted or deleted answers will also effectively neuter a user by way of the automatic filters that are built into the system.
There isn't really any need to drag every potential spam account into Meta, as it would quickly drown Meta in essentially identical posts. We also don't want to essentially start a vigilante mob going around handing out "frontier justice" to potentially innocent users who are just trying to help. The system has plenty of ways to keep things tidy without naming and shaming.
Moderators have access to tools that can assist in identification of problem users and take necessary action.