Agreed. Here's a snippet from a
recent conversation elsewhere:
What's hard-to-reverse about an OCLP/APFS installation btw? You simply erase the drive and install something else as I've done several times.
B.S. Magnet beat me to it: “Sir, this is a Starbucks…” --The average Mac owner (in another thread, I previously estimated at least 90% based upon examination of machines turned in to recyclers) no longer know how to even display their drives on the desktop, as Apple has hidden them by default since the early California OSes.
It's not hard for smart people like you and me, because guys like us have piles of spare externals laying around and generally know what the eff we're doing. But the average user who runs OCLP even once is going to have that bootloader pop-up greeting him permanently thereafter, and if he decides he hates the glacial performance of a 32bit-killing APFS OS and wishes to revert, then setting up an external, Migrating to it, booting from it, wiping the internal, and then cloning back to it.... ...well, because he's average, he'll end up bricking his system at some step along the way, and my phone will start nagging me after midnight because I was an idiot and forgot to turn it off.
Put in one of these, then Mojave/HFS+ in a generous-sized first partition. Install Parallels for Mac, then explore various Linux and Windows distros in Parallels.