Many people I've met really could use more fulfilling hobbies.
Speaking only for myself, my more fulfilling hobbies feel like a zero-sum proposition when I factor in taking care of myself, my kids, my home, etc. What little leisure time activies I pursue are almost all pursued between the hours of 9 and 11pm, because that's the time I have.
I think the OP is right in a lot of ways, that work has replaced our other social outlets. But its also the case that just existing costs more, so time formerly spent on hobbies is now spent on basic lifestyle maintenance, and the time formerly spent on basic lifestyle maintenance is spent working, or commuting to/from work (because a lot of people can't afford to live near they work).
And yet, most people have hours every day available to spend watching movies, YouTube, etc. That is time that could be spent doing something fulfilling.
As someone who tries to spend most of my days after work making games, there are days I just don’t have the mental energy to do it. And there have been months where I haven’t worked on it at all, as work and things in my personal life get more stressful.
Its the same story as "I can't go to the bank if they're only open when I have to be at work", but for mental health rather than finances.
I wasn't making a judgment (though I wasn't explicitly not making one either), just saying that many people could use them. Hobbies are good identities, and many people feel a need to define themselves but struggle to do so.
That said, I do know people who complain about having very little time, but I know they spend 4 or 5 hours every day on television, video games, and social media. They don't own a home, they don't have kids, they get on the TV as soon as they get off their 40-hour-a-week job, and complain about how they can't afford the time to have hobbies. Excuses exist on a spectrum of reasonableness, and some excuses are more understandable than others.
The majority of people I know who really want to have fulfilling hobbies do have fulfilling hobbies. Many of them work long hours, also have kids, have to take care of their home, and the like. They'll still scrounge together a few hours a week to paint some Warhammer figurines and decompress.
Most people would also benefit from occasional therapy or a personal accountant. It's not accessible for everybody, but the fact remains.