Coaches are the employers of officials. They have a right to evaluate their employees. Whether their opinions influence your progression depends on your official's association. Their opinions should be taken into consideration but should not be the final evaluation.That should be the job of your league, conference or Association Evaluators whatever applies..
In my experience over 40 years as Referee, Clinician and Evaluator, the great officials all have gained the respect of their employers.(The coaches). Respect the game, the coaches, their players and fans and you will succeed as an official. Show disrespect to any of those 4 entities and you will not progress.
Good communication skills are one of the most important attributes of any official..

While I agree with your comments concerning gaining the respect of coaches I don't consider them the "employer" of officials.

The bottom line is the people that provide the referee financing are generally the teams (ie coaches, organization whatever) and they meet the definition of employer. Having been a coach I know I at least represented the employer and was expected to speak on his behalf. A mute point.

If a coach ever represented him/herself as my employer it definitely would become a mute point, because the converstation would end immediately.