The banking syndicate takes on some risk in order to facilitate trading in a successful IPO. Usually to compensate for this risk the IPO price is (slightly) less than what they believe the stock will trade at. This way the IPO investors and the banks can make a bit of money for bearing this risk.
It's usually seen as unsuccessful and a bad-news story when a stock falls below its IPO price. Even though Lyft might have taken the max from investors, it will diminish its ability to raise further equity and its bankers will lose the trust of the IPO investors.