Earlier this week, Instagram CEO Kevin Systrom announced onstage at Europe’s tech conference Le Web that the popular photo-sharing start-up was killing support for “Twitter cards.” As Twitter explained in a post, this basically means when users click Tweets with an Instagram link, photos will show up cropped and incomplete. Eventually, those photos disappear from Twitter altogether. Users will only be able to post photo links to the social network that reroute to Instagram.com.

Systrom’s reasoning? “We want to direct users to where the content lives originally,” he told the conference audience, claiming that the recently revamped Instagram.com, now with web profiles, provides a better user experience. In other words: Instagram is purposefully handicapping the Instagram experience on Twitter so users will go to its own website.

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From a purely business perspective, the move make sense. Amputate your product found elsewhere, and loyal users — of which Instagram has over 100 million — will be likely to go to the source, in this case, Instagram.com. And pulling Twitter card integration is hardly the first contentious move Instagram has made. It’s actually one of several. That doesn’t mean it is not surprising, given the ties the two had: Twitter co-founder Jack Dorsey was an early investor and advocate, and it’s fair to say Instagram owes some of its early, rapid growth to features enabling users to easily share those digitally filtered snapshots on Twitter itself.

Earlier this year, the relationship soured. Instagram, which was reportedly (and seriously) being courted by Twitter for acquisition, got snapped up by Facebook (FB) last April in a landmark deal then valued at nearly $1 billion. Three months later, Twitter effectively disabled Instagram’s “Find Friends” feature that let users find one another. Now, as The New York Times reports, Twitter is developing its own photo-filter and sharing feature, one that would arguably compete directly with Instagram itself.

Although Systrom has said the move is not intended as a form of “retribution,” it’s hard not to view it as anything but. Meanwhile, Twitter’s own aggressive behavior is understandable given Instagram’s new owner, which in recent months, has made visible strides to beef up its own photo features online and on mobile.

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But ultimately, whether you’re an Instagram user who dips into Twitter, a Twitter user who just skims Instagram photos in their streams, or an avid user of both, it’s hard not to feel like the loser in this none-too-subtle vitriolic exchange where features are crippled for purely selfish enterprise reasons. I, for one, don’t want to use Twitter and have to click on a link to another site to look at a photo I once could have viewed on the site. Regardless of whose fault that is, it makes for a poorer experience. (Heck, even Systrom has said the change may be “really confusing” to users.)

So until Twitter rolls out that purported Instagram-like feature, and Instagram sorts out its big online web push, expect things to possibly get even more heated. And who suffers the most — certainly not Twitter or Instagram — but users.