Why does every website seem to use max volume level for sound?

I don't know if the title is clear but whenever you visit a website which has a video or audio on the page, the player's sound level is always set to max. I never see it set to a conservative level by default.

It creates this bad experience of sudden loud noise until you can silence it or mute your PC.

Is this not a bad design? I am sure nobody uses max sound levels on their computer. Because if their software was at max level, then people would increase the amplitude on their speakers/receiver and then set the volume on their computer back to a moderate level.

So I don't understand this notion of "let's set the video player sound to max by default".