The author briefly touches on a pet peeve of mine:
> Every single time, I have to swap the default currency from USD to CAD. Why can't it remember that I'm Canadian??
US-based devs and English-speaking devs often forget about the rest of the world. Either it's bad or inexistent i18n, overly broad assumptions (e.g name=`${firstName} ${lastName}`) or just straight-up bad default values that can't be changed (like the example).
When you're developing a SaaS, more often than not you're doing it for a global audience. Don't forget that.