They didn’t preface this comment with “lmao”, genius. Someone asked “what’s so funny?” in response to the first “lmao”, and ayrt responded by saying “lmao is because”. Meaning “I’m/they’re laughing because...”. Explaining why someone said lmao the first time by saying why isn’t them just using lmao as a mere preface. Would this have been clearer if they had started the comment with something like “I/they said lmao because...”? Sure. But what they’re trying to say with their first sentence is still pretty clear to those of us actually reading their comment.