"Consider the fact that STEEM went from 7 cents to $8.5 from March 2017 to January 2018."
This is for me a sign that the supply curve of Steem and now Hive is rather flat as supply is rather flat. Either people sell at any price anyway or they do not sell at all as their Hive is powered up. This shows me that a small shift in the demand curve might result in a huge price increase.
Most STEEM and most HIVE and are on exchanges. 220 million HIVE are liquid (including HBD). The vesting fund is only about 150 million HIVE. There is, in fact, so much liquidity on the markets that even if all of the inflation were sold immediately, the difference between inflation rates of 8% and 4% per year would be practically insignificant.
There is A LOT of dumb money on the cryptocurrency markets. The last big bull run of STEEM too took place after Bitcoin had rallied first. People who either made big fat profits on Bitcoin got greedy and some people were late for the Bitcoin train bought SBD and STEEM hoping for a pump, which took place. That's how the altcoin market works. In a way, they are a means to making leveraged plays on Bitcoin. There is so much volatility in HIVE that most holders prefer not to power up their coins. A whopping 200 million are kept on exchanges. Inflation rates simply don't matter much. Altcoins are not digital gold.