If you kept reading you'd see that the previews are actually generated by the sender. So it's unlikely there's any privacy leakage happening at all.

But even if there was, I'm not sure why you're assuming that someone would need to get their head checked if they are using a default feature.

Even if you turn off link previews you would still receive link previews. You just don't send the link previews.

which is why it should be opt-in, not opt-out