It may not be appropriate to compare research from two different researchers owing to the difference in research designs. At the same time, in certain types of research settings (for eg. panel data analysis), it is possible to compare the results and research methodology employed. It could help young researchers to understand the suitable methodology to choose in various research settings.
The comparison among researchers can be done on what is visible to the research community (this is somewhat different from an institutional comparison). The basis for comparison is the scientific achievements of the researcher, his breakthrough results, and the value of his achievements to society.
Nowadays the good research is expected to publish in a high impact factor journal, therefore such kinds of comparison are being made among the researchers. Every good researcher talks about SCI journal, so comparison in such an environment becomes natural.