A worthwhile distinction to make when discussing this topic is that of the classical definition of inflation (growth of the money supply) vs the modern definition of inflation (price surge). Monero, like gold, is inflationary in the sense of the first definition only, not the second.
Annual tail emission forever being less than 1% of the total supply and the equilibrium between lost coins and newly minted ones are the two phenomenons that prevent the latter—loss of purchasing power— from happening. I feel like many people talk past each other arguing about this because they simply hold different definitions of inflation.
