Since I can remember I've always been a social outcast with little to no contact with the outside world. Hiding in the bathroom in gym class or refusing to take the bus because there were other kids. I've never had any social media either and only leave my room if necessary. For the first couple of years I was oblivious to it all and just enjoyed Xbox 360 with no care in the world. Xbox Live, and to a lesser extent Steam, was my only form of contact with other human beings. I never made a Youtube or anything to communicate with others although I'd lurk. Throughout middle school and high school I was a basement dweller gaming all day and night when not in school. Around this time I developed a habit for talking to myself replaying conversations I overheard among others and indulging in detailed fantasies often daydreaming for hours.
Then people stopped playing Xbox games like Halo 3, my online friends stopped getting online and I got bored of the sames games. My Xbox breaking was the final nail in the coffin. Since then (2013) I've relied solely on the chans and Steam for my human contact.
Around 2015 I fully came to realize my situation. Isolated with no more online contact besides anonymous posts. I was talking to myself more to the point of full blown conversations and couldn't resist. Crying alone in my room thinking about my life and depressed. I began to believe I may have had special supernatural powers due to the synchronicity I was seeing everywhere. I lost touch with reality. Then I was kicked out by my mother and had to get a job.
In short I'd say isolation can really cause you mental and emotional distress, but only if you're actively aware of it and see it in a negative light.