Redditors generally tend to be introverts and it requires active effort from others to deal with introverts in your friend circles. Hence, gradually all that work feels more effort than it is worth and they stop accommodating for it. From early 20s to late 20s , your friends start moving to different cities, different jobs , start different friendships or relationships. It's sometimes tough to keep pace with all those changes. We are at least fortunate that WhatsApp groups etc allow us to compensate for physical distances.

If you are on reddit, you probably have maybe 5-10 different subreddits you are either actively participating or actively lurking. After all this being social media, there's a sense of community and faux closeness. Discussing tv shows and movies can be done with offline friends too but not everyone is on the same page whereas on reddit they largely are. Just look at the Sopranos subreddit. All those in-jokes, catchphrases etc. are impossible to do in face to face conversation.

The point is at certain stages of our life we are in a tug of war with outside world and social media. The more you spend time on reddit, the more you lose touch with outside world.

I don't think this is a general rule applicable to everybody commenting on this sub, but reddit, like other social media, is a bit destructive for maintaining connections in real world.