What is the point of a Letter of Interest?

I know this may be CRA specific but why do staffing processes send out a letter of interest, just to seemingly select pre-determined candidates?

I recently got one that was an at level lateral move to a different department within my office. After selecting ‘yes’ I was interested, I answered 3 application questions (using all the tips from here), just to be told 2 months later that they gave the positions to 6 people already within that department. All were lateral moves. There were no interviews, no assessments etc. They just gave out the jobs based on 3 questions. The process advised there would be no recourse because no pool was created.

My question is why do they waste everyone’s time when they seemingly know who they want to give the jobs to? Management has no problem giving out acting assignments without running a process so why do they run these ‘faux’ processes to select candidates? It’s really soul-crushing filling out an application just to find out you were never in contention for the job anyways.