Like the repeated hook of a pop song that you can’t get out of your head, mergers between the already-powerful wireless giants keep coming. In the previous greatest hits category of wireless consolidation, the Obama administration managed to stop the music for a while: Its DOJ blocked AT&T from buying T-Mobile in 2011, and a 2014 effort by Sprint to merge with T-Mobile was rebuffed by regulators. But the beat goes on, as rumors are swirling this month that Sprint and T-Mobile will soon announce plans to merge.

Susan Crawford is a columnist for Backchannel and a professor at Harvard Law School. She is also the author of The Responsive City and Captive Audience. Sign up to get Backchannel's weekly newsletter, and follow us on Facebook, Twitter, and Instagram.

This 2017 merger reprise—an attempt to revive the bad old days when harmful acquisitions were shooed past regulators—should also be soundly rejected. The problem is not just that we’d have three instead of four wireless giants in the US, though that’s certainly a major issue. An even bigger threat to the consumer is what would happen next. As I see it, a Sprint/T-Mobile combination would inevitably end up being a wholesale partner for our giant cable companies (Comcast and Spectrum). The resulting business deals would allow those behemoths to neatly control many segments—wired, wireless, prepaid, post-paid—of the stagnant and expensive connectivity marketplace in America. That isn’t a future we should want.

The players have gotten so bloated that it’s hard to remember who owns what—so let’s review the landscape. AT&T-DIRECTV is about to become AT&T-Time Warner in a few weeks, with former AT&T telecom executive John Stankey becoming the overseer of HBO, Warner Bros., and the rest of Time Warner. AT&T, with its nearly 135 million wireless customers, wants to be a vertically integrated content delivery company. Verizon, with its nearly 150 million wireless customers, pursued its own content dreams by recently swallowing up AOL and Yahoo.

We’ve long had a “duopoly with a fringe” among American wireless companies, with AT&T and Verizon dominating just about everything (and accounting for 67 percent of the post-paid market). Today, T-Mobile is third in line with about 72 million customers (17 percent of the market). Sprint has about 59 million (15 percent). According to the FCC, the four companies together account for virtually all of the US wireless market. Structurally, that’s been the case for years.

But something interesting has happened in the past few years with those two smaller players. In 2011, when the DOJ and FCC blocked AT&T’s proposed merger with T-Mobile, AT&T had claimed that T-Mobile was too small to compete effectively on its own. Since then, T-Mobile has continued to change its business model, adopting unlimited data plans and offering consumer-friendly innovations in the handset subsidy market. Along with Sprint, T-Mobile now has a huge presence in prepaid, mobile, data-only plans for people who don’t want to sign up for multi-year contracts or who have poor credit (and so wouldn’t qualify for monthly plans). It’s doing pretty well on its own.

Combining Sprint with T-Mobile would give the resulting entity most of the market in prepaid plans—not great news for poorer (or just price-sensitive) people who now can play off Sprint’s prepaid Virgin Mobile USA and Boost Mobile plans against T-Mobile’s MetroPCS prepaid offerings. The combined entity would undoubtedly have power to raise its prices for these plans. And, of course, a market with just three players would find it far easier to coordinate prices overall than a market with four players would—that reasoning hasn’t changed since 2011.

Wireless is already a “highly concentrated” market, to use DOJ terms, and any merger that substantially increases concentration in such a market is presumptively anti-competitive according to the DOJ’s 2010 Horizontal Merger Guidelines. A Sprint/T-Mobile merger would do that. (And indeed, Bloomberg reported last week that staff employees of the Trump DOJ Antitrust Division were leaning against the deal for this reason. But the buzz from insiders is that the staff lawyers will be overruled by their managers.)

As I noted earlier, that’s only the more obvious reason to bounce this proposal.

Additionally, a combined Sprint/T-Mobile would provide a truly nationwide operator with lower-band spectrum and an enormous presence in the prepaid (poorer) market. And that would set the stage for deep and unpleasant consequences not only in the wireless market but also for overall connectivity in the US. That’s because, though most don’t realize it, the wireless and wired access markets are not hermetically sealed off from one another. True—wireless, with its relatively low capacity and high price-per-GB can’t compete effectively head-to-head with wired; it’s no substitute. But it is a complementary segment of the overall connectivity marketplace. It’s data that is in demand, really, not content: People want more mobile data.