The answer is found in System Preferences > Mission Control. Uncheck the “Automatically rearrange spaces based on most recent use” box :)
Funny, i really like this because it lets me switch to another app and then return with a single swipe. The ipad has this behaviour too though the swipe is in the opposite direction.
I use full screen very heavily and rarely use spaces as separate desktops, which I find weird. You probably consider my use weird.
Not to say one approach is better than the other, just suggesting whoever set the default might have decided based on their own use. I suspect this issue was not subjected to any UX research, even at a place as big as apple.
And you're correct, I never use full screen. I don't think it's weird to use it, it just doesn't suit my workflow (single large monitor, so I need a lot of stuff side-by-side).
If it didn’t rearrange based on use the animation would show an arbitrary number of moves and you would have to keep track of how many times it moved over to know how many times to swipe to get back.
If you only change desktops by using Mission Control rearrange based on recent used shouldn’t even be a problem because it will never automatically rearrange if you use Mission Control.
My ideal setup would be that a user NEVER gets switched into another Space/Desktop, even if they click an icon in the dock, or Cmd-Tab. If there's a window in Safari in another space that I wanted, I would switch sequentially to that space and find it.
I do like to hear how other people work and if they like features that I don't; helps me gauge how far along on the curmudgeon timeline I am!
As for myself, I don’t use Spaces at all.
I have a keyboard shortcut for every application I use daily. CMD+CTRL plus a letter, M for Mail, T for terminal, B for browser… And so on.
Some keys are “overloaded” via Keyboard Maestro, like editor “E”: If MacVim is open, use it, otherwise open TextMate (Not using both much these days since switching to VSCode, which inherited “V” after I ditched Voodoopad :))
To make this work ergonomically, I have to be able to press CMD+CTRL with either the left or the right hand. So the first thing I do with new Macs, is remapping the right Option/Alt Key to Ctrl via Karabiner.
Using this system for the past 15 years, my worst fear is that one day Apple will close down its system so much, that this simple remap will no longer work - they are already on the hunt for kernel extensions…
Always thought it was bug, turned that straight off.