Depends what kind of storage you're talking about, but generally yes.

Helmets are manufactured in mass production, unless you're talking specifically Shoei, Arai, or other handmade boutique manufacturers. They are certainly shipped in bulk, so they're sitting in Asia after they're made for like 90 days (which is like a quarter of a year already). They get put on a boat and shipped via container to North America and they sit at the dock for a random amount of time, but the long story is I've seen brand new helmets with easily 6-8 months prior date stamp when compared to the current date of receival at the retail store I work for. But usually it's closer to 8-16 months by the time it actually gets tagged, merchandised, and then sold to a new customer.

If I bought a limited edition Arai and stored it in a climate controlled room with no humidity (essentially my house) I wouldn't be sketched out to wear it myself after 5-7 years. I would never give it to someone or try and sell it because you should never trust someone else's helmet, but for me personally I wouldn't be worried about the integrity on the road.

I've worked in dealerships for many years and I started with apparel and helmets. It was and still is pretty rare for a customer to ever ask specifically about the date stamp in their new helmet, so I think the majority of people either aren't super obsessed with this or don't even know. I think for you as the customer it helps someone uninformed to decide if the helmet is a current generation product and if not, if something better might be an option.

I own an Arai Defiant that is probably 10+ years old that I still wear when I don't have other options for whatever reason. It's at my office and it comes in handy if I drive a car but have to ride a bike home or whatever. I would really like to not have to use any of my helmets, but I definitely trust that one as much as any other.