Initially, LOL was a way to signal “I don’t really mean it; I’m being funny,” as in EXAMPLE ONE:
Person A: I love the new Beck album!
Person B: Not me, I hate it. It sucks as much as your taste in music, LOL.
Rather than just agree, Person B makes a little game of faux-disagreement, then makes sure the reader understands intent by adding the LOL.
This was a modest-but-efficient bit of stage direction WAY back in the Jurassic era, when Bill Clinton was in the White House (LOL).
In example two, we see that LOL does still convey meaning, but in such an obvious way that it is unnecessary. You *might* have misunderstood and thought that Person B didn’t like the new Beck album. You’re unlikely to think that I really think the Clinton administration was contemporaneous to the Jurassic era.
But now LOL has gone from adding unnecessary tone to actually SUBTRACTING meaning from the utterance in which it appears, as in
Person A: Whatcha doing?
Person B: Not much. Making a sandwich, LOL.
In usage of this sort, the person really is eating a sandwich. There’s nothing funny about that fact. People eat sandwiches. And there’s no irony or nuance of tone to be understood.
[I grant that there may sometimes be such nuance in context-specific communications if, for instance, the two people have engaged in some kind of sandwich-based humor in an earlier conversation, and the LOL accesses that…but I doubt that’s what is generally going on].
Generally, I think Person B has gotten used to texting “LOL” and now does so reflexively, like a tic, for no good cause and to no good effect.
It seems to me like a very fast evolution, from helpful meaning-enhancer, to unnecessary meaning-clarifier, to distracting meaning-subtractor, LOL.