There are two notable differences between when the AGI-posters do it and when IRC-posters do it. AGI-posters extend their lowercase posting to what would normally be seen as more formal communication. They also tend to stick to using punctuation despite the lowercase. IRC posters usually keep it to informal communications, where it's a sign of casualness. That said, there is overlap, and it's of course not possible to instantly distinguish someone as a Sama devotee because of how they type; but it is clear that a lot of people in that bubble are intentionally adopting the style.