It's not just the liquidity. They'll want to see 2+ years of work history, pay stubs, debts, monthly payments (rent/credit cards/mortgage/etc), tax returns, etc. In short, if the math doesn't show that you can make the payments (without the benefit of renters), you don't get the mortgage.
You might buy one house. Maybe two, depending on your current job/income. You won't get five. And, if you're self-employed...forget it.
It was looser before the mortgage collapse, but still not what you're describing.
Most of those "As Seen On TV" get-rich-with-property schemes try to sell you on the idea of brokering deals for other people, not buying the house yourself...at least not directly. Not that they aren't full of shit as well