Did reading the whitepaper stop at that sentence for you? Because when you keep it in context, it makes a whole heck of a lot more sense:

"At first glance, 100% annual increase in the STEEM supply may appear to be
hyper-inflationary and unsustainable. Those who follow the Quantity Theory of Money may even conclude that the value of STEEM must fall by approximately 5.6% per month. We know from countless real-world examples that the quantity of money does not have a direct and immediate impact on its value, though it certainly plays a role."

"Because 90% of all STEEM created is distributed back to holders of SP, the result is similar to having a 2:1 “split” every year rather true inflation. The total rate of expenditures used to reward contributors is about 10% of the market capitalization per year, a rate well below what Bitcoin sustained for the first 7 years after it launched"