Not necessarily! But it's true that if at suitable moisture levels when packed, and heat sealed properly, and subsequently stored in a cool dark place (the light less an issue obviously), they do work very well over periods of months, but I don't know about a year or more, but it would not surprise me if they came out in pretty decent condition, with maybe a slightly more sedative side with a bit extra CBN, but essentially good to use and no serious degradation. But that is an educated guess, so I'd be cautious if it's large amounts, maybe go glass, but test an eight in a bag in the meantime, to see for the next time around? One thing to watch though, if it gets sealed in with some mold spores, and is damp enough, you may open a bag of ruined weed without having any way to know! In the glass jar, you can unseal and reseal easily, and visually examine without opening. In terms of being probably the most suitable material for storing almost any chemical or mixture short of hydrofluoric acid and the like, glass is damn tough to beat, plus can be unsealed then sealed up again, the bag method means filling a new bag if you need temporary access.
But alternative to vacuum, why not look at seeing if you can get hold of a mini gas bottle of nitrogen or a similar noble gas (though nitrogen's far cheaper), and just flush the bag/bottle with the gas to push out most of the O2 before sealing up. Really it's not vacuum if talking about a plastic bag of some sort, it's about sucking out most of the air, which isn't quite the same thing, as you noted.
But also consider this, if you use a largish container, and fill it as much as possible without damaging the weed, then just seal it airtight and leave it at that (assuming it's humidity is already good). Yes, there is a bit of oxygen in there, and yes, it will oxidise some of the cannabinoids and terpenes in there, but, it's only going to be a tiny fraction and I bet if you never opened it until the end, you'd never be able to tell it hadn't been vacuum or nitrogen stored. It's repeated opening that's the worse thing as it refreshes the oxygen again and again.
If I had to bet I'd say the difference between a Kg stored under nitrogen for a year, and a normal vacuum sealed plastic bag (of suitable material) kept cool and dark, you'd not see much difference after a year. With these things, as a very general rule, it's a matter of diminishing returns. So, minimise the oxygen, keep dark and cool, and you've probably cracked 90% of the task if you've done it well (are the lids really air tight, etc.). You'll have to work much harder to get another small improvement beyond that. Of course quantities matter too. Is it work the effort for an Oz? Probably not as much as for a ton! I have to wonder whether it would be better to just bung the stuff in the freezer in a sealed bag and leave it at that?