JIF bloats because of review articles that draw a huge #citations
. As a result, amazing journals like Inorg Chem, J Chem Phys, J Phys Chem, PCCP etc that publish less review articles have stagnant, single-digit JIFs. It's a bad game to be honest.
Citation imbalance: Reviews versus articles
See how various contributing elements impact the Journal Impact Factor (JIF) in this latest editorial