It puts your claim on the record
A press release is an attributable company statement with a date on it. A journalist can quote it. A partner can forward it. An investor running diligence can cite it. A founder interview or a social post does none of that reliably — the wording moves, and it is not attributable to the company.
It also means every journalist works from the same facts: the figures, the spelling of names and job titles, and the quote your spokesperson actually approved.