Banks did us a disservice in the past decade as they lent money to people who couldn’t afford their mortgage payments. Then they foreclosed, leaving properties vacant and uncared for, degrading neighborhoods. At the end of it all, in many cases, the banks recouped less in the foreclosure than they would have if they had worked out payments the original borrowers could have actually afforded.

The brilliant minds at work in that scenario now have another predatory move up their sleeves. They’re out to destroy retail districts. The banks don’t see this as their aim, but this is the result if they infest our neighborhoods with their blank windows.

Beacon Hill is seeing the worst of it right now, but other downtown neighborhoods are at risk. As much as North Enders complain about the noise and traffic from their restaurants, they would miss those annoyances if the restaurants became a line of bank windows.

Beacon Hill already has five banks, one credit union, a stand-alone ATM, and several other ATMs in shops throughout the Hill. On its edges are four more banks.

But Capital One wants to move into the prominent corner of Mount Vernon and Charles streets, displacing a small, heavily patronized convenience store. It’s not clear as I write this how that situation will turn out, since there was a huge demonstration of opposition to giving the bank relief from a quirky zoning problem. And spokesman Jimmy Hernandez confirmed that TD Bank is angling for a space on Cambridge Street, probably the large empty space at 250 Cambridge Street. Broker Martha Abrams-Bell, who, rumor has it, upped the price when a bank became interested, did not return a phone call.

These possible new banks arrive after the Hingham Savings Bank replaced an antique store on Charles Street and a People’s United Bank occupied space on Cambridge Street last fall.

Interestingly, no one has yet seen a customer at either of the new banks. It will be hard for them to attract a significant market share on Beacon Hill. Part of the problem is the banks that are already here, especially Cambridge Trust. Cambridge Trust’s warm staff, their participation in and support of the neighborhood, and that bank’s policies means that it already has as customers many of the long-term wealthier residents’ and most of the local businesses’ business. The new banks’ most likely customers will be students and short-term younger professionals with small accounts and few loan needs.

But these new banks may not want customers. During a recent meeting at which Capital One presented its plan to the Beacon Hill Civic Association’s zoning and licensing committee, the Capital One representative did not answer a question about why his bank wanted to come here. Instead he described how New York neighborhoods had opposed their presence but had become accustomed to it.

Real estate broker Ivy A. Turner, however, set the audience straight on why banks want to come. She said they don’t care so much about market share. They want a retail branch that acts as a billboard for their national expansion goals.

Why is that so bad?

It’s bad because a bank or other office sucks the life out of a retail street. It takes up space that otherwise would provide needed or desirable goods or services. Unlike a restaurant or a grocery store, it closes at night, and anything closed makes the sidewalk in front of it more dangerous. It provides nothing interesting to look at, an important part of the pedestrian experience. It offers nothing for tourists, who bolster Boston’s economy. Its deadening demeanor dampens the whole block’s vitality, causing neighboring shops to lose business. “No bank or real estate office creates value in a neighborhood,” said Jesse Baerkahn, a retail consultant who has been instrumental in the revitalization of Kendall Square.

Why don’t we object to Cambridge Trust, which would have the same effect? They were lucky enough to find a storefront that is near a major retail street, but not on it.

In sucking the life out of a community’s center, banks and other offices destroy the very reason they want to locate there in the first place.

And make no mistake about why we live in downtown Boston. It isn’t just because the neighborhoods are “tony,” as some media outlets like to insist.

We live here mainly because our neighborhoods are convenient, saving us time, money and anxiety. We don’t have to commute. We get everything delivered. We aren’t paying to heat a big single-family house in the suburbs, but a smaller place with only a front and a back exposed. Our pedestrian-friendly, serviceable commercial streets mean that when we do errands, we walk, we can wrap up our responsibilities in just a few minutes and enjoy seeing our neighbors while we do them. One of Boston’s most livable characteristics is that it has a lot of these neighborhoods, from the downtown to outlying places like Brighton and Roslindale.

So how do we keep our neighborhoods’ commercial districts vibrant, walkable, useful and appealing?

We rezone every commercial street to make ground-floor offices a conditional use, a process the BHCA has started. We refuse to do business with brokers or banks or any other office occupants that take over a space where a shop has been. We make known to building owners and potential office occupants that offices on the ground floor will meet hostility that will affect their bottom line.

Let’s off the banks before they off our neighborhoods.