You can download the factory image on SamMobile.com and use Odin to install the software. Yes, you can re-install the OS if you soft bricked your Samsung, however an error will occur if you try to downgrade anything lower than the current version. Back then, they allowed you to do that, however nowadays you cannot because they don't want you to. You can still downgrade if you rooted your phone somehow but that's another story. Keep coming up with excuses for it all you want, truth is they don't want reverse engineering and discourage repairs and instead encourage purchasing new devices.
BTW I do know what I'm talking about, I've used Samsung ever since their infancy for 6 years plus I worked at Best Buy and Samsung. Here is the page to download Samsung factory images:
https://www.sammobile.com/firmwares/