Do you know who says "l8"? People who are rude and have no regard for anyone that might be a bit out of the loop. Someone who says, "This was posted a while ago." isn't bad since they're at least being moderate about it. However, someone saying "l8" or "so l8" is rude and inconsiderate since they didn't even take the effort to write a proper sentence and instead had to resort to Internet shortcuts. Note that saying "l8" doesn't contribute to anything and instead is spam. If you've seen it before, just ignore it instead of going out of your way to insult the person.