They framed their argument like enjoying those perks was a symbol of immaturity, which is what sets the condescending tone.

I love having a good cafeteria for breakfast and lunch. Going out to eat is such a massive time sink and you really should eat with your coworkers where possible. On-site gyms are the same, if I'm already going to the gym after work, why make a special trip?

It doesn't mean that you're stuck at work the entire time. In fact, I'd argue that it can reduce your time at the office, if used right. Use your breaks to run some errands that you'd normally do after work. Schedule your workout for 3:00-4:00 if you have a meeting that runs a little later. Etc.

You can be a fully functioning adult and still enjoy those benefits.