By Kirk Miller That floating QR code during last night’s Super Bowl was certainly memorable. But the ad proved so popular that it knocked out the company’s app — which maybe isn’t great if your company depends on technology. As reported by Inc., Coinbase’s 60-second minimalist ad (well, not minimal in cost; while the production value was close to nil, buying time during the game cost roughly $7 million) was so successful it crashed the cryptocurrency exchange’s app, which was promoting $15 in free Bitcoin if you created an account and $3 million in giveaways. Coverage of the ad’s genius (it wa…