This is my experience as well. Most "friends" only stay friends for as long as they share activities together, and if there is too long of an absence in activities, it will be harder to plan activities or reconnect later down the line. They'll usually drop down to acquaintance level and stay there. Goes for work, hobbies, and more. Friends who stick around for who you are, rather than what you do together, are exceptionally rare. Especially later in life, when everyone is "too busy" for activities outside what they already do.

I hope my experience is the minority, as the increasing loneliness that seems to be present as the younger generations grow older to me indicates the over reliance on work for friendship is the exact opposite of what we need. And on a much darker and more cynical level, it provides an opportunity of social manipulation for companies to keep one tied to their job at a lower wage, or risk crippling loneliness.