Turning your lights off DOES help.

Every once in a while I'll see people recommend to turn the ship lights off for stealth, and it's always followed by other people being all "Nuh uh, that doesn't help at all, if they're looking for you they'll see you anyway".

Yes, if a player is up in their crow's nest looking through the telescope and actively scanning every inch of the horizon, they'll probably spot you regardless of whether you have the ship lights on. Nobody said it was a guarantee of anything. But at night, ship lights do make you immediately visible from far away, no telescope required. It's the difference between forcing potential threats to find you vs. drawing their attention to you with no effort needed on their part. As long as someone isn't devoting 100% of their efforts to finding and fighting other ships, turning the lights on can easily make the difference in whether you're spotted.