There's an economic argument for steady inflation as a counterweight against compound interest and debt.

Inflation creates an economic incentive for productive investment. I'd rather own a $20 machine that generates $1/year of new valuable goods/services than a $20 bill in a vault, because the goods/services will inflate in value while the cash will not. And if I don't have $20, I'll be willing to borrow it if the value of the debt declines over time while the value of my annual production rises.

When wages match inflation rates and surplus cash can be productively invested, each new participant in the economy has an opportunity to grow their personal fortunes over time.

However, when wages lag inflation, only the early adopters get to see the benefits of new productivity. Old money compounds faster than new wage earn investment enters the pool. And eventually you get a Berkshire Hathaway / Goldman Sachs / Blackrock / Citadel style superfund that owns a significant percentage of virtually everything.

The same thing happens in deflation. People with access to cheap credit or liquid currency (banks, mostly) can horde capital while wages contract. And then, again, you end up with an economy in which a handful of feudal aristocrats hold the titles on all the properties.

But when wages grow faster than inflation, you see the reverse. Earners can buy into property at a steady discount, while investment of new properties promise higher yields than simply sitting on old capital stock indefinitely.

There's an economist named Thomas Piketty who breaks it down thoroughly in Capitalism in the 21st Century, detailing why you want the economic growth of your national economy (G) to exceed the rate of return on investment (R) if you care about reducing overall economic inequality.

why is inflation necessary again?

stock market go brrr

If a company makes less profit than last quarter, no matter how many billions in profit that actually comes out to or how satisfied the customers are with the company's products, investors will be sad and the line will go down. If a company makes more profit than last quarter, the line goes up regardless of if that growth is actually sustainable long term because that's not our problem right now. All that matters is we can tell investors we had record profits this quarter, the executives get to take home their million dollar bonuses, and the line doesn't go down until after those execs leave for even greener pastures.

So, a company can't just be good at what it does at the scale that it does it, it must grow constantly like a cancerous tumor in order to stay attractive to investors. When people are flush with cash you squeeze it out of them as fast as you possibly can because, again, the future doesn't matter right now and anyways they'll just give it to someone else if you don't take it first. Sell products that don't last very long so the customer keeps coming back. Raise prices and cut staff when times are anything less than stellar but never under any circumstances lower prices or give workers more than the lowest amount it takes to keep them working, because that means less profit which means the line will go down which means the execs don't get their bonuses and that is a fate worse than death.