The gold standard was the basis for the international monetary system from the 1870s to 1971 with some brief interruptions. Before that, other commodities were used as the underpinnings of the monetary system for as long as humanity has utilized currency. These are all deflationary currencies. In fact, inflationary currencies are a relatively recent invention. The one notable feature it has is that depressions don't seem to exist (instead being converted to bad recessions). That being said, it has only 50 years of history behind it so who knows how stable it is in the longer term.

I'm a huge crypto skeptic because the cost/benefit isn't there for the amount of pollution it creates and the amount of crime it enables, not because it's a deflationary currency.

In what world is gold deflationary? The supply of available gold generally increases. The difference is that the expansion of the supply of gold is less flexible and harder to control.

Gold is also vunerable to supply shocks. For those weak on history, I suggest learning about the effects on global currencies due to the european pillaging of the Americas for precious metals.

Also, nothing prevents cryptocurrencies from having a mint rate that makes them inflationary. You don't really see that much because all "currency-like" projects with cryptocurrencies are still fundementally about inflating a speculative bubble to get early adopters rich.

Complete nonsense. A currency is an asset, and an asset is neither deflationary nor inflationary, since these terms refer to its price, which is determined by the market and is therefore not an intrinsic characteristic of the asset.