Even without electronics, beyond age of 6, nearby areas are explores quick and indoor activities are more fun then biking alone again through area you know pretty well. I knew few kids who liked that, but they were very much minority - and they were the kind of kids that don't seek novelty and aresponsibility fine with doing the same thing same way every day. Even without electronics, over age of 6-7, indoor has more options, more interesting options and is more fun unless there is company outside. Hence kids not rushing outside if a chance of meeting someone is low.

Not a good friend is a kid you don't like to play with. It is simply not true that all kids like to play with all kids nor that all they do is games and games are the same. It does not have to be something bad like bullying or being little assholes - through it can be. It can be something as simple as one kid doing mostly focused plays and the other widely running around. With many kids they will sort themselves to groups, with few they just end up doing own thing and not having interest in each other.