There are no thoughts, it's programmed to not be first come, first serve. I dont mean to come off as harsh but that's literally how the system is programmed

It's just pure luck. If its 300% overloaded, 1/3 people will still get a spot in that class. The algorithm also ranks people according to preferences and clashes as well. It's possible some people had clashes and had a better chance of getting the spots than you.
The strategy
is to use clashes, so, i think that also may have been your issue.
To summarise: It's more or less totally random whether you get a spot in an overloaded class. True first come, first serve, would be to allow signup at Monday 9am like Melbourne uni does. Who ever hits the button first gets in. Allocate is far better in that there is a lag time in entering your preferences and the program sorting them once it closes.
I've never actually gotten a horrible timetable so maybe i've just been on the really lucky side of those odds. A few times i haven't gotten a few of my preferences but it happens. The university is simply bursting at the seams and they've just gotta try ration all the places out.