Seriously though, I'm gay so if I want I can literally go to a sex club and have sex, but scrolling is 100 times better than sex with a random person.

IMO the problem isn't that we choose scrolling over sex, but that having a smartphone makes independence easier, which removes opportunities and motivation to meet people. People talk to each other mainly when they need to solve practical problems. Remove practical problems and you remove social interaction.

I remember clearly that when my ex fixed my bike I had a strong impulse of being attracted to him. But realistically, when my bike is broken, I'd rather take it to a bike shop than ask someone for help and then do favors in exchange.

Also should note that this is a working paper and not peer reviewed. Working papers are circulated to invite comments and discussion. Until some experts confirm their methodology I wouldn't take any of this for granted.