Mycorrhizal networks, to pick just one of myriad counterexamples, would like a word. Decentralization is just something that humans are (so far) bad at designing for.
> paying with crypto is always going to be more painful [than fiat] unless you use an exchange
Always is a long time. As governments figure out how to add features to fiat via CBDC's I can definitely image some bloat that would make paying in fiat needlessly complex. It's not like cryptocurrency has the market cornered on bad decisions.