I know this is a sales tactic, and until 2013 I would have refused. (Also depends on the item and cost of warranty, risk/benefit.)
I was SHOCKED that I could find the water heater papers from 10 years ago in 30 seconds. (And I’ve had a lot going on in those 10 years that would say I couldn’t.)
For me, the trick is having one or two dedicated spots (if possible) for all instruction manuals, paperwork, etc., no matter the item. Currently, I have two.
The first spot is in my home office: one file rack. The other is the corner of the dining room hutch. I tend to put the high ticket items, warranties, and receipts in my office—I don’t look at the water heater instructions often, if ever, and I don’t want to lose the receipt or warranty.
Things that I need to refer to the manual for and lower priced items (may not have extended warranty) I keep on the dining room hutch—easy access and handy to kitchen, laundry, etc.
I’m the only one who touches the stuff in my office. Other family members can use manuals on hutch and replace.
There is a store that has a smart policy IMO, if you do not use the extended warranty, they give a 50% credit toward a future purchase (most likely you will need one of their appliances before you die!)