There's a pub in my city where the staff greet you when you walk in and actively encourage you to sit at a table that's already occupied. If you come in alone you'll probably end up sitting at a two person table where inevitably there will be a stranger right across from you, with a couple similar tables right next to it. Of course if you want to be alone you can go sit in a corner somewhere.

Needless to say everyone starts talking to each other after a drink or two. This bar is enormously popular. I've never seen it not be packed. It's an incredibly successful strategy for them. With all the complaints about the death of third spaces, I'm baffled that more places don't do this. I see no reason a cafe couldn't do it as well.

All this to say I think it's a great loss that younger people aren't going to bars as much. I wouldn't say they're the best way to form deep connections, but I have zero fear of ever lacking random social interactions, because I know I can just go to a reasonably busy pub in the evening, sit at the bar, and sooner or later either I'll start a conversation or someone else will. It's also a great way to get good at handling opinions that are different from yours - if you have a thin skin or live in a bubble, being subjected to drunk people from every walk of life will rectify those issues quickly lol.