There is no advantage. You would be contributing some empirical facts that don't really answer any interesting question. It could be a useful educational exercise in bibliometrics, though.
It can give interesting data about where authors come from, what subjects are most popular, the growth of its subject area, what the academic links are to its own and other disciplines, etc. However, do be aware that the journal's Impact Factor is a very misleading figure and should not be relied on to assess the journal's quality.
Usually, the bibliometric studies are useful to understand the nature of a considered discipline over the past years. If we limit this to a particular journal as in your original question, the findings would be limited to the considered journal. Trends of research (based on text analysis), co-authorship patterns, citation analysis, bibliographic coupling, co-citation analysis, and so on are the common study areas of bibliometrics. However, we should not forget about the limitations of these studies. First, the databases that used to obtain data usually include limited publications, limited coverage (subject-wise and year-wise), limited types of documents, limited data types, and so on. Second, the limited features of the tools that used to analyse data may also hinder to obtain the exact results you want to find.
The advantages of bibliometric methods for scientific assessments are very obvious; the methods are simple, because were based on simple counting. Many techniques have become particularly easy in the digital age, because their execution can be automated.
Hello, in Mexico, bibliometric studies of journals are carried out individually to know their impact, visibility and try to obtain institutional resources. An example of some cases can be seen at: http://bcct.unam.mx/metrics/pres/estudios/
In fact, it has no advantages for the relevant scientific society, especially for a short period. For those who are interested in objective metrics in relation to journals, HEIs, researchers, and countries' research performance applied bibliometrics and scientometrics data is satisfactory. Additionally, The editorial board is informed about the status of the journal in comparison with the competitors. however, in a long time span, it is useful for tracking trends in a subject area considering core journals.