They created toggles to differentiate between settings that take place immediately vs being deferred until a later Save action. If you accept that premise (you might not!) then the problem isn't toggles per se but that the toggles are displayed in a way that makes the current and alternate states ambiguous.

In case you're wondering, macOS didn't have them until they started fusing it with iOS.

The use of grayscale is a bit disingenuous.

Gray is not the default color theme on macOS. The default is blue. So the criticism about using right/left to distinguish on/off doesn't really apply. In reality, the use of color disambiguates the on and off states. Just like the physical toggle example it's being compared against.

That's not to say there aren't problems with toggles, but the article's core argument falls apart if you use any color theme other than gray.