It is hardly a "weird" definition. Economics and "the economy" as a whole fundamentally deal with scarcity.
Figuring out the most appropriate use of a good or service given that its scarce and has a multitude of "other" uses is the core problem that capitalism tries to solve.
Do you assume scarcity of resources is required for there to be a scarcity of products and especially services? You may still want to have someone cook you dinner without there being a scarcity of food. There is still art and stuff, live performances you may want to see. But no scarcity of resources, no need to fight for survival, the motivation to always optimize for profit at the expense of everything else
That's the definition of value storage. The economy works on greeds, realization of greeds, and creation of new greeds. Scarcity would lead to the greed of owning it.
Intro economics class our teacher posed a question "Would economics exist if everyone had a magic wand that could get them whatever they wanted?" I said "ya, cause someone would magic other peoples wands away then there would be an economy to restore peoples wands or grant wishes on behalf of people." Apparently that wasn't the answer they were looking for, but he said I might have some point. I think people just like messing with other people and that is inalienable.
In developed world, we already have all the goods we want and need, we spend a lot money on services. It is kind of like the world your teacher described :)
Figuring out the most appropriate use of a good or service given that its scarce and has a multitude of "other" uses is the core problem that capitalism tries to solve.