And what benefit is the company getting from saying a person that is not going to contribute to the company in any way is an “advisor”?

I guess the company should just do that with every former employee? I mean, why not.

This is the behavior of a person and company playing startup and not actually trying to build a strong company.

Probably because founders tend to have strong influence over a company and tend to have their share of personal fans and supporters among the userbase. So they try to avoid alienating them by pretending that they still get along.

Like when Carl Pei left OnePlus, we all knew it would go to shit once Oppo took over but they kept up the pretense for a while to protect the brand before they started undermining it.

For the 'advisor' there's probably a financial arrangement to this to keep them quiet and from shoveling up dirt in the media. It's hard to just give someone money like that so again a fake role comes in handy.