Recruiters from other companies can also find people with immediate need of job which fits jobs openings.
Is is something startups can use?
However, I must admit that HR portals are rabbit holes that looks good on paper, but then fall into one of two problems: chicken and egg, or garbage data. You need to have very clear strategy of how both sides of the job market are encouraged to adopt a new "empty" platform, while making sure that job listings are actually clean, truthful, and relevant.
Are you saying that founders will input the resumes? It sounds like a lot of work, and not something I'd expect a person with a failing project on hand be able to do.
In MVP, I was thinking someone, may be a founder or person who can help, will fill simple details. Later stage, they can send invitation links to employees to fill in the details.
Probably there is niche, but m not able to validate this idea.
Sometimes the entire team gets hired all at once.