When you buy a house, for $1 million or $50,000, the normal case being described in yours and the parent post is that you are buying a house on margin while using the house itself as collateral for the loan.
If you show up at a house that is for sale and ready to be sold with a million dollars in cash -- well, a million dollars in easily-authenticated cash equivalent -- and ask to buy the house as-is, no conditions or concerns on your part, you can make a deal happen markedly faster. Not microsecond fast, because why, and the sellers might balk at such a weird transaction or shop around to see if they can get another seller at a higher price, but once you take financing and any sort of buyer-protection out of the equation it basically comes down to registering the sale with the local registry.