Typically, referrals have positive impact like making sure your application gets looked at by a human and possibly tips a "maybe" into the candidate's favor for scheduling a phone screen or moving to the next round of interviews.
There are plenty of very talented people with large networks of former coworkers who will attest to their capabilities and give them referrals, who nonetheless are still struggling to find work.
I am a well networked person and I cannot offer any help to the numerous people (who are all great, many former colleagues or even alumni who could slot right in and help us) who are reaching out to me for even just a referral.
My employer has seen record breaking quarters and years and we have nothing open in engineering or even IT or support. In fact, I can already smell the blood in the water from the layoffs that are surely coming, probably shortly into 2027.
I had two friends refer me for bog standard senior engineer positions with a stack I had experience with and they ghosted me with no explanation to my friends.
My other friends in faangs say if they refer someone they’re not allowed to be involved in the hiring process at all.