I'd argue that the connection is that owning real estate here is not as heavily supported by the overall tax and financial framework. Two examples: Mortgage payments are not tax-deductible and and you are personally on the hook for the mortgage, as in you cannot send the keys to the bank and simply walk away without debt.

Those are also true of the UK with its massive property bubble, although curiously landlords can deduct mortgage from tax but owner-occupiers can't.

I think the real difference is that Germany has proper tenant's rights and a functioning social landlord system.