Well, the problem is not availability .... in theory, Ukraine has really no shortage of equipment. The problem is how much is operational. You can have 1000 armor, but only 20-30 of it being operational. That's the issue here. Sometimes its cheaper to just buy new equipment than repair everything. I think people often vastly underestimate how much effort it takes to repair, maintain and mobilize a military during peace and war time and supply it with sufficient amount of material and supplies. Fuel is a massive problem. Lot of vehicles can't be operated just because of fuel shortage. Ammunition is a problem, replacement of outdated, old, cut, distorted wiring, electronics etc. Smaller armies suffer such issues, now image an army with the inventory of Ukraine, Russia etc and a certain degree of neglect over the decades. That is why for war, you only can mobilize so much, that is combat effective, and not more, even when you have "millions" of troops. The distribution of equipment, ammo and supplies must be efficient.
Smaller force + good support, logistcs and supply >>>> Larger force + moderate support, poor logistics and limited supply.
However yes, indeed. Having such massive reserves of equipment is good, especialy when you have a heavy industry that is capable of putting everything back on track. But that is a mammoth task, and I can imagine Ukraine's military industry and economy suffering quite a lot from the ongoing crisis.
