It is all about Control.
Exxon Managers seem to want full control over every aspect of careers to ensure the sponsored ones flourish with artificially highest rankings and best job opportunities to help support those artificial rankings.
EXxon immediately stopped Job Postings by Mobil affiliates at the merger.
EXxon Managers freaked out at the thought of publishing a list of open jobs every two weeks and letting employees express interest in the ones they wanted.
Exxon Managers also freaked out at the idea of eliminating forced ranking like the system Mobil used.