The internet is part of it (a crutch or surrogate, a reason to not leave the house, a quick time-filler that doesn't require extra space or money), but I think that outside factors are bigger. For instance I live in a semi-rural area and don't have a car, so I don't really have options anyway (particularly not wanting to spend money). If the internet went out today I'd just be really alone and with nothing to do.

Also the decline of social capital hasn't been so bad everywhere, and wouldn't you know it the countries that have the most social capital seem to also be the ones that also top other charts like for happiness or healthcare outcomes. The ones that some people in the US look to as an example for better policy and society structure.