Instagram made good on its promise to delete fake and spammy accounts this week and caused an uproar among Instagrammers stunned at their plunging follower counts.

The purge, dubbed the Instagram Rapture, has hit celebrities the hardest. Justin Bieber lost 5 million followers, 15% of his total, and Kim Kardashian lost 1.3 million. Rapper Mase reportedly dropped to 100,000 followers from 1.6 million in a 20-minute span and then deleted his account.

Follower counts are not just an matter of vanity; they are a form of currency o the network as high-profile Instagram users trade on their influence to sign promotional and endorsement deals. That has sparked a black market for Instagram followers, the New York Times reporting in April that a million followers could be purchased for $3,700.

Instagram warned last week the clean-up was coming, noting that the spammy accounts had already been deactivated for violation community guidelines and weren’t being counted among its 300 million active users.

“When we remove accounts from Instagram that don’t follow our Community Guidelines, you may see a decrease in your follower count,” the company wrote in last week’s blog post. “This shouldn’t affect engagement from authentic accounts that like and comment on your posts.”

For marketers, the purge is good news. Now brands and businesses will have a clearer indication of how many people they are reaching on the Facebook-owned photo sharing network.

And brands seem to have taken less of a hit in loss of followers. Web developer Zach Allia created an infographic tracking the follower drops for the top 100 Instagram accounts and no brand on the list lost more than 5% of its followers. Well, no brand except Instagram itself, which lost nearly 19 million followers, 29% of its former total.

Nike, for instance, lost 256k followers or 2.8%, leaving it with 8.7 million. Forever21 lost 245k (4.3%) and now has 5.3 million. GoPro shed 93K (2.5%) and now has 3.6 million.