How can it be personal attacks. It is simple logic. I give you a simple example -> The research conducted in certain countries usually is based on industry needs of the country. In China, for example, the have demand in the technology of space exploration and High-speed rail. So you’ll see a lot of research being churned out speedily by a number of local researchers due to the immediate demand in the country. You’ve touched about ball bearing tech, for example, and this is an example of recent research article for that which could be beneficial in the HSR areas. When those people in the same country citing each other, we can’t simply claim they’re doing it as a matter of convenience. It could be an indicator that the subject itself is the top priority in the country.

Another point to consider -> If the journal where the article have been written is in the Scopus index, there’s even low probability for the work to be of low value, no matter who has been citing them.

Of course that the general idea, but there’s still room to debate.