OG names are names that are (and always were) in high demand, and therefore were quickly taken. The fact that your name was still available means that it wasn’t in high demand. OG names are being pilfered because they are in high demand and therefore highly valuable.

It’s like trying to register a .com domain - OG ones (short 2-4 letters) are only available in the aftermarket, and only if you have millions. You end up with along-ish name that’s also taken - so end up with domainhq or .io or whatever is popular now.

Because all the good obvious ones are already taken. Simple ones like "kevin" or "a". Unless your name is super unique, your username from the last 4 years has some sort of quirky thing, like a weird spelling with extra letters or numbers to get around that.