SAN FRANCISCO (MarketWatch) — After an extended drought of credit available to consumers, it’s going to get easier to buy a home.

The Federal Housing Finance Agency this week polished off a new set of guidelines that will allow government backing of loans that it had shunned since the mortgage crisis. And in a surprise move, the guidelines include a provision to consider some mortgages without down payments.

And Mel Watt, the FHFA director, said earlier this week that Fannie Mae and Freddie Mac are planning to guarantee some loans with down payments of as little as 3%. That should help underwater homeowners.

Let’s begin by saying that’s not necessarily a bad thing. There are instances where loans should be available to borrowers without the means to place a down payment. It’s just that I can’t think of any.

The FHFA and the Obama administration are both worried about the amount of credit available to the average American. It’s an epidemic problem. About a third of housing sales were to cash buyers in the first quarter, according to the National Association of Realtors. As I’ve written before, this is extraordinarily high, indicative of a housing market that favors the wealthy.

“ Borrowers can no longer depend on banks and regulators to measure creditworthiness. ”

So by lowering the standards of what types of loans are acceptable to the big mortgage giants, it’s obvious that the FHFA’s effort is about encouraging banks to provide more loans. The government is essentially saying: “Go ahead and lend; we’ll hold the paper.”

But in trying to ease credit and turn a mythic housing recovery into a real one, the FHFA may be overreaching.

That’s because you know exactly who’s going to be taking out those loans: people who can’t afford them. And because there will always be some people who believe that because they can borrow, they can afford these loans, you know how this new policy is going to play out.

Consider a study issued Oct. 13 by mortgage data provider HSH.com. It found that 80% of homeowners had a regret about their purchase. Surprisingly, most of the regrets weren’t about costs. They were about the size of the home, the neighbors, the schools and other gripes. Then again, this was a post-foreclosure wave survey of 2,000 homeowners. The more than 4 million borrowers who lost their homes to foreclosure since the crisis probably weren’t asked and would have different regrets.

So, while the FHFA is certainly opening the door to another mortgage problem, it’s not ultimately the one to blame. That falls to the home buyer who bites off too much.

The risky and often deceptive practices of big banks and brokerages, along with the inept efforts of regulators, usually take a pounding in this column. But it’s important to recognize that borrowers can no longer depend on banks and regulators to measure creditworthiness. Historically, it was difficult to get a home loan. And down payments weren’t an option. They were the price of admission to the lending officer’s desk.

But a series of government programs, low interest rates and tax breaks along with loosening standards at banks eroded this institutional test. So today it’s incumbent on the borrower to ask himself if he can afford the American Dream.

For many, the answer is probably “no.” The U.S. median household income is $51,900. The median home price is $188,000. So, yes, it’s possible. But the current home-buying market is full of cash buyers and speculators, many of them hedge funds. That means in many markets, there’s competition for properties from buyers who will outgun regular folks.

The FHFA will, in the end, encourage more lending. And this will translate into more credit for people who have been denied. But that policy isn’t the one that matters. It’s my policy, your policy, based on what we truly can afford that does.