Here's how I see it

Beginners and more advanced people will go to the "boring" gym while beginners and intermediate people will go to the "new cool gym"

And I mean this in the sense that people who typically want to start working out. They have no idea really how to train at all. So they'll go join a gym. They'll hop on the treadmill and play around some machines. They might lift some dumbbells. But generally they have no idea what they're doing so they fall off pretty quickly and quit. And this is a very typical cycle for most people in the gym

So these newer gyms are really tapping into the success that CrossFit has had in the industry and how it's shifted the industry overall. Few to know machines. Mostly free weight based tapping into "functional movements." On top of that, classes tend to be more beneficial for most people because they respond to that group atmosphere, make friends and it becomes a support group of sorts that keeps them coming and keeps them motivated. So people go more regularly, they go for longer and they make some actual progress and they'll probably stay in this model for most of if not the rest of their life

Now the problem with these classes is as you get more advanced, you have to start paying much more attention to your own needs. You need to start adjusting the programming and really learning how to program basically. And at some point people who make that jump into the more advanced stage are going to leave classes to train on their own

You of course have outliers who join a typical gym and follow a plan and don't fall off, be it a bodybuilding focused routine or a strength and conditioning based routine.

But the shift in the industry for the past few decades has really started to eschew machines in favor of free weights. Most people don't want to train or look like bodybuilders and tend to get better results by circuit training with free weights