My impression for the popularity of the 75% form factor is due to laptops and people being accustomed to never have used the "missing" keys in the first place. A tell-tale is that default layout even for thinkpads is to set the Fn row to media keys by default... An increasingly smaller number of people use them, despite being a row of freely remappable keys right _there_.

What I've seen happen though is that especially on linux you need two-modifier combos (ctrl-shift/ctrl-alt) to perform what you could have done with a single Fn keystroke. Or burn a few extra keys and increase complexity with layers. I went this route a decade ago, and I'm not a fan personally. Removing the Fn row saves 2cm of vertical space from your desk. I see it as completely pointless, even if you never use the Fn keys.

And I don't buy the "reduced finger travel" argument either. Holding the modifiers in weird positions to access an extra layer is usually worse than a more spacious keyboard where your hands can be kept further apart and require less chording.

But yeah... I commented on another thread on keyboards, and the current keyboard craze is mostly about customization and looks, and very little about the actual typing experience IMHO (there are exceptions of course..).