The "free weights vs machines" argument is as old as the first machine. It's also like the proverbial asshole -- everybody's got one.
A few things I know. One it depends 100% on what you want. Lifting is you vs the weight, not you vs anyone else's opinion and/or capability. Chasing someone else's capability unless you are a professional competitor is dumb and usually non-or-counter-productive.
I get caught up in the mentality of comparing what I used to lift to what I am lifting and calling it "baby weight". In context, I am stronger than the average man. I never remember that part when I'm looking to 1 rep max with a weight I used to use for a warm up
What I know about the argument is this: There has been one, professional weightlifter/bodybuilder/power lifter that I know of that claimed to build his body with machines. That was Casey Viator back in the 80s, a competitive bodybuilder and Top 10 in pro events for a few years. The claim was he built his body using nothing but the Nautilus weight machines. A LOT of people were skeptical. For one, Arthur Jones who invented both the Universal and Nautilus machines was footing his bill to pimp his stuff
From personal experience, I was a regular at pushing over 300 on the bench on the Universal. First time I tried free weights (heavy ones), I got 185. Serious ego crush
The science behind it is free weights require a lot of auxiliary muscles machines do not. You have to balance the weight in free weights. On machines, you have only to move the weight along the predetermined track. If you drop it, it makes a lot of noise but you can jump away from it and no harm no foul. The free weights you have to be in control of from start to finish. You can seriously injure yourself or someone else if you drop a weight/miss a lift with free weights. So you have to also add in the mental stress of knowing that. And stress DOES matter when lifting.
As far as who decides what equates to what, who knows?