If you wanted to say "most of what's on Google Fonts is bottom of the barrel", you'd have a colorable argument. But that isn't what you said.
System font from a web standpoint means you get one of these depending on the user's choice of phone, desktop, and/or browser.
It is somewhat like buying art because the frame covers a blemish on the wall. That the print inside the frame might be of a famous impressionist painting does not mean that the frame or the print necessarily go with the room.
The car analogy involves a car rental place - that they may give you any one of several newish, functional and even stylish vehicles does not change that you may often wind up being paired with a vehicle mismatched for your function.