So as I read it, some folks do this almost for fun/the thrill of getting a deal? Not judging, just noting it.
For some it is.
I admit there is a "thrill" getting a deal sometimes, but there have been many deals I have passed on since I just don't need the oil (saw some 0w-16 on clearance for a dollar a qt at Walmart, but passed since I have no need, same for some 20w-50 for almost free).
I have a ton of oil for OPE as I use it heavily. But cars not so much. Things change and now I buy a few weeks before I need it. No advantage hoarding oil that may not be applicable to a new ride.
I guess if you change vehicles often enough it could be an issue.
I have had the same truck and car since 2012 ('02 F150 and '12 Scion), and added 2 vehicles ('18 Santa Fe and '04 Sonata).
I also have no plans to buy anything in the next 5 years that requires anything newer than API SN and I have no issue going a weight above or below what is "recommended" by manufactures.
My stash of xw-20, xw-30 and xw-40, all SN or SN+, will be perfectly fine for my uses for quite a while.
As I mentioned before, I will be needing to buy some oil very soon for my Goldwing (decided to not use the Rotella 0w-40 I have in my stash in it), and am hoping for the next Mobil rebate to start tomorrow, otherwise I will have to pay full price (first time is years to pay full price on oil) on the Mobil 1 HM 10w-40 that I want for it.