It's an idea from Lean management. Everything you need to keep, prevents you from keeping something else; requires you to remember where it is, where you could be remembering something else; takes longer to move when you have to move it; takes longer to organise than having less would. It poses fire hazards that having nothing wouldn't pose. Blocks light that having nothing wouldn't block. Keeping stuff is inherently wasteful.
None of this is to say that keeping stuff is bad. It may be very useful to keep it. But you should always recognise that doing so incurs a cost that you need to trade off against its usefulness.
While we're on it, inventory is one of the eight kinds of waste identified in Lean. They are:
Transportation
Inventory
Motion
Waiting
Overproduction
Overprocessing
Defects
Skills (misuse of)
Remember TIM WOODS.
All of this is meant for running a factory, but I've found a lot of them useful in other bits of life, especially the idea that Inventory is a form of waste.
I guess the context in which this is applied to makes the difference.
In my home, I'm fine with keeping inventory when it makes sense.
Non perishable food, for example, has it's own happy place in a corner of my home that wouldn't otherwise be utilized. Stocking up on this inventory has demonstrably saved a lot of money vs. buying when needed.
During covid, my stockpiling years before allowed me to essentially not run out of anything or pay a premium on things that were either not available or overpriced during the first year of the pandemic.
Keeping a stockpile also means that I'm not wasting time, gas, energy, or money running out multiple times a week to pick up necessities. I just take from my inventory, which would be at a lower price than the current price, and I move on with my day.
If I had to only buy certain things when needed, I estimate that I'd likely be overspending by at least 30% + whatever time and transportation costs to make those errand runs.
No disagreements here! What you're doing here is recognising that the waste incurred from storage is less of a problem than the waste incurred through Transportation, or Waiting for resupply. In this case, inventory is waste worth doing. Any workshop needs to keep SOME spare parts, every house needs to have SOME food in the freezer. But that doesn't mean it's not a kind of waste to store stuff -- a fact people acknowledge when they choose not to rent a warehouse to store even more.
What I'm saying is that it's a trade-off. In fact it's a pretty bland statement, obvious when you think about it, but putting it into words like this can be helpful when making processes more efficient.
Not just stores, but inventory of goods in general. The thought is that resources spent on inventory are resources which could have otherwise been spent elsewhere. This line of thinking and fixation on Just-In-Time goods deliveries was one of the most important factors in the supply chain fuckery around covid, which only began to stabilize last year.
excess inventory is waste. Always have a buffer to handle shenanigans and/or be able to source the next thing,and avoid being up shit creek the next time the TP truck is a week late.