I understand the sentiment, but if it's coming from a reputable source I'd disagree. I think it's ideal to understand the commands, but most users occasionally need to do some things that they'll never learn what the commands do but they need to use them. It's like saying never to run an application you download from somewhere. Sure, ideally you don't unless you've read through the source-code and double checked it's the same thing, but no one's doing that.

You're scaring yourself away from these experiences. If you managed to pick the parts out for a computer then you can assemble it. Picking them out and making sure they're compatible is the hard part. Assembly is just putting them into slots that only they can fit into and plugging in some wires.

Installing an OS is also (usually) trivial. You download the software online and put it on a USB drive and follow the instructions. Dual booting takes a little more effort because you have to set up partitions, but it usually isn't that bad. I'm 100% Linux though because when I dual booted starting from Windows it eventually destroyed things after a Windows update (because Windows sucks), so I just removed the Windows partition and redid everything with just Linux.

If you want to try it, you can use a VM like VirtualBox, unless you have an ancient potato PC.