The web was created to knock down walls. You could create a page on a Unix workstation in Switzerland that could be viewed perfectly on a Windows laptop in California, all thanks to the miracle of common formats and open standards. But lately it seems like the big social networks are doing their best to undermine this sort of compatibility and to integrate products vertically much as behemoths like IBM and DEC did 40 years ago.

The latest evidence of this came in a series of striking announcements over the past week, as Facebook, Twitter and Google+ took steps to fortify their own photo apps and features at the cost of competitors'. Though the issue of web photo compatibility was solved 19 years ago, when browsers like Mosaic and Netscape standardized on the GIF and then JPEG file formats, the top three social networks are putting lots of money and effort into building end-to-end pipelines in which one company’s software controls everything from activating the camera to polishing the image to uploading the photo to setting access rights and finally publishing – not necessarily to the web, mind you, but to gated-off private networks that merely resemble the web.

And the social networks seem to be using their pipelines on an increasingly exclusive basis. Facebook, for example, altered its photo app Instagram this week such that it no longer publishes photos to Twitter in the same rich, native fashion in which it publishes to Facebook. Instead, Instagram now sends Twitter users links which pull them back to Instagram/Facebook to actually view pictures.

Imagine if Ford built freeways where other makes were banned – that’s Google+. Imagine if the Chevy Malibu drove at half speed on anything other than Chevy freeways – that’s Facebook’s Instagram.But don’t cry for Twitter. The microblogging platform just unveiled its own photo-editing system, integrated into the main Twitter app and, naturally, only sending its output to Twitter. There are lots of independent apps that want to send edited photos and other content into Twitter, but Twitter has increasingly been cutting them off, both by subsuming their functionality and by curtailing the platform-interface access it provides them.

The most vertically integrated pipeline belongs to Google, which makes the mobile operating system (Android) that runs your mobile device and its camera, the software used to edit and export your picture (Snapseed), the social network used to host the picture (Google+), and in a few cases even the network used to upload everything (Google Fiber). And Google is not above locking out rivals: Google+ is the only of the three biggest social networks to have a read-only developer interface, meaning that outside apps (like Facebook’s Instagram) cannot publish into the system, as Google-owned Snapseed gained the ability to do this past week. To Google’s credit, Snapseed, technically part of the Google+ division, runs on the competing smartphone platform iOS and can export to competing social networks Facebook and Twitter.

All the walls popping up between the rival social empires are getting absurd. Imagine if Ford built a series of freeways where Chevys, Hondas, and other makes were banned – that’s Google+. Imagine if the Chevy Malibu drove at half speed on anything other than Chevy-owned freeways – that’s Facebook’s Instagram. Imagine if the California state freeway department Caltrans started building their own cars to discourage people from driving around in the half-speed Chevys – that’s Twitter.

Perhaps all this vertically integrated empire-building is meant to conjure the success of Apple, which made big money defying PC industry trends and building its own stacks of hardware, operating systems, applications, and internet services. But Apple used its vertical integration to pioneer amazingly innovative approaches to relatively young markets – for MP3 players, smartphones, and tablets. Even then, it often had to back off its proprietary instincts, as when Steve Jobs reluctantly agreed to allow third-party apps onto the iPhone (and thus eventually onto the iPad).

The concepts behind social networking were, five years ago, as fresh as those behind touchscreen tablets are today. Back in, say, 2006 it might have made sense to be conservative in working with outside developers. But patterns like friending, following, liking/favoriting, and groups/lists/circles have since become familiar.

If the big social networks keep playing empire-building games at the expense of users, the users might just decide they’ve had enough and build something unexpected that steals momentum from all the big players. That’s happened repeatedly over the past several decades, longtime software developer and blog pioneer Dave Winer reminded me over lunch in New York last week. Just think of IBM and Microsoft in the 1980s, and AOL in the 1990s.

If history is a guide, even companies as mighty as Facebook and Twitter can be quickly displaced by a set of scrappy newcomers, born from disgruntled former users. Hacking together new software to take on Facebook doesn’t sound particularly fun. But it sure beats living like a serf.