If you're already inclined towards isolation, like I am sometimes, driverless taxies will help with that. But if you're inclined towards going out and doing things, which I also am sometimes, there are few incentives more alluring than a fast and cheap way to get from point A to point B. If labor and gasoline are removed from the equation there's no reason rides can't be ridiculously cheap, and spending $20 on a round trip instead of $80 lowers one of the biggest barriers for going out (at least in urban areas and/or when drinking/drugs are involved).

I can spend more times at my friend's place, maybe have a beer or two without having to worry about driving back - so I think it encourages socialisation

I'm not sure if you mean about Waymo/self-driving cars or more broadly, but I'll assume you mean cars. Let me first say I'd love to create a list of all of the long-term pros and cons of self-driving cars because I'd be far better-equipped to answer, but my off-the-cuff thought: this technology, if it survives, will make it easier, safer, less stressful and less costly for people to transit, and will also make almost every place more livable (the impacts will be more profound in urban areas than rural, but both will benefit). That sounds like a great way to increase interactivity, not lessen it.

Uber sometimes offers a service called UberPool where you share the car with another passenger in order to save money right? Couldn't Waymo do the same?

How is that different than if you were driving yourself?