It depends greatly on the goal of the website. If the only goal is to convey some textual information, sure go with "sans-serif" or "serif" or "system-ui". But your website will look different on every OS.
If you want any form of design and consistency and do not want to use a web font, what are you left with? I think Arial and Times New Roman ship with every Windows and Mac release...Linux likely not?
If you want any form of design and consistency and do not want to use a web font, what are you left with? I think Arial and Times New Roman ship with every Windows and Mac release...Linux likely not?