I was referring to the composition and post production (sound design, engineering) world. Mostly because that is the industry I worked in for many years and still continue to work in (much more sporadically these days).
That's a world that was dominated by Mac Pros around 2010. Around 2013 I started seeing a shift, myself included, to custom built PC workstations and that trend is just increasing now. The initial switch, I believe, started with the lackluster cylinder Mac Pro, but continued due to the obvious failings in the Mac desktop market.
You speak of home based studios using MacBook pros, but anyone doing that is obviously not a professional. I will give you the fact that many DJs are using MacBooks for the mobile rigs, but at home, anyone actually doing professional audio work is likely using a massive powerful workstation or a number of PCs (master/slaves).
This notion that MacBooks (or even laptops in general) are super popular in the professional audio world is fiction made for advertising.