Elon dismantling PR makes sense. Probably they rubbed him the wrong way too often. Why bother.
When the other car manufacturers finally catch up to Tesla, the negative perception of the Elon Musk brand may drive some buyers away from Tesla.
Wasn't that his public goal?
Steve always use his brand to sell Apple. Elon always use Tesla to sell his brand.
TL;DR - They manage one single external voice. There's value in that. As other point out, Musk is a communications study in and of himself.
Simple: PR teams are some sort of equivalent to the "triage" at emergency rooms. Basically they scan incoming requests for stuff that could land the company in hot legal water or signalize a coming shitstorm (e.g. if journalists ask for information regarding potentially damaging stories during their research), misdirected customer service stuff (pretty common, especially in companies ... not exactly known for decent CS reps), youtubers/other influencers looking for merch gear, shareholders inquiring about financial or other information, movie makers / photographers interested in showing off company products, reps of athletes wanting a sponsorship deal... all of this usually goes through the PR dept who forward it to the appropriate departments or answer on their own.
The key role / function of a good PR team is that the individual departments don't get flooded by bullshit (you don't want to waste the expensive time of the legal dept on a youtuber wanting a Tesla for a rap music video).
https://www.polygon.com/2019/8/18/20811014/apex-legends-iron...
But as Tesla doesn't pay for advertising (unlike its ICE competitors), the incentives are not aligned, so Tesla and the press had bad relations for a long time.
The press tends to be antagonistic toward any big company. Good PR counteracts that, in part by finding and helping the members of the press who like the company.
No company was better at PR than Apple under Steve Jobs. They carefully groomed key reviewers and helped build up a pro-Apple ecosystem of media properties.
Edit: I should add that Apple's PR under Steve Jobs was led by Katie Cotton, and her dept. was famous for rarely responding to direct requests for comment on the news of the day.
It's also great to talk to the press when the story and the company's goals DON'T align. If a company is being investigated or impacted in some negative way, then not commenting looks worse on them.