If your bicycles are purely for recreation you maybe can get away with not having any spare parts and if you have to wait 3-4 weeks for a chain or BB maybe that’s OK. But if your bicycle is your main commuter or grocery getter it only makes sense to have some tubes, a tire or two, a chain, some cables and housing, brake pads, and maybe a bottom bracket on hand. Even without the part shortage you tend to discover these things need to be replaced 8pm on a Sunday night.
Even after COVID I don’t think things are going back to the way it was for manufacturing goods, ever. The future of the underlying assumptions that allowed off-shore manufacturing and frictionless supply chains spanning half the world and multiple countries (a functioning global order, US military and geopolitical hegemony, stable US political culture, and technology as an unalloyed good) are in grave doubt and it will take a while (ie years) for companies to internalize the new reality. COVID just accelerated this, it was already happening.