It's a dumb thing to do too. If you have a website, you control what it says. For a shop or restaurant it's totally fine to just show a nice photo with your name, opening hours, address, and contact details, and just link to whatever social media accounts and reservation/delivery ordering platform you use.

It's also the place that will allow you to inform your patrons when big tech deletes your heavily invested in social media account for some reason.

Not having a normal website means that potential customers who search for you get hit by login-walls for Instagram and Facebook if they're not on it, or 'you need an app for this' with crap like TikTok. It also makes my (volunteer) job of mapping the area around me harder, because I'm most certainly not going to bother to enter any additional info about your business if I have to go to Instagram or Facebook (and in the OpenStreetMap community I'm not alone in that).

My experience is most restaurant websites are either outdated, offline, or hacked and showing some malware page. While the social media page is up to date.

While all of then problems you list are real, small restaurant owners don’t have the time or skills to run a website, having a social media and listing on the maps apps is enough.

I agree. If a business decided to only be on Facebook or Instagram, then they're choosing the path of hiding themselves from the open web. I wouldn't even bother to update their info on OSM.