The typical user could use something other than Infura - but they don't.
The typical user could use some future system that doesn't exist yet - but they don't.
The typical user could cash out somewhere other than Coinbase - but they don't.
The typical user could use stablecoins other than USDC - but they don't.
This is covered in the article already. Default behaviour matters, a lot. Almost no Ethereum users are going to telnet 30303.
Same argument can be made for key management. A typical user could use non custodial wallet, but they don’t. But that option exists, for when they become unsatisfied with their centralized wallet custodian, or when they want to change custodians, or when they want to use a multi sig that allows for a mix of custodial and non custodial.
Importantly: the option exists. The option to use non custodial EOA and smart contract wallet, DAI or RAI, Alchemy or a custom node RPC, Kraken or another CEX or DEX, the option is present and is chosen by plenty of users.