The money will have to be exchanged for goods (which usually don't store that long, so need to be produced fresh) and services (which don't store at all). If each generation wants to stop working the next generation needs to produces these things.
But a lot of the expenses each generation has are for example housing, food, cars. So sure, that method doesn't hedge against the price of services or fluctuations in whatever you invest the money in, but neither does the current system. Current system is exposed to inflation, FX etc too. It does at least hedge against [working vs retirement age] population which is one which definitely varies. Basically the current system is going to screw my generation (in the UK) because we're paying off our parent's triple-locked gold-plated pensions, which we are definitely not going to receive. So we'll be the one that pays for ending the offset.
(In a small country you could use the savings to import good from abroad of course)