It’s dumb and doesn’t tackle the root of loneliness. If they’re lonely, they need support to find new friends.

If they have trouble making friends, and it’s not due to their own personality being toxic (like being an incel, creep, borderline, or generally an asshole), then they also need support in learning how to socialise.

That doesn’t mean they’d have to socialise, just that they learn how to do so, and so have a way out of their vicious circle. Best way to make friends as an adult (so, no school/college/uni), is to go to the circles where you have mutual interests.

So, go sport together. Take up an hobby. Schedule meetups with the people you like and know online.