I find it really interesting that abbreviations online have abandoned sound-based abbreviations (is there an actual term for it? Things like “c u l8r”) in favor of actual abbreviations for things that have nothing to do with the content itself and are more like qualifiers (lbr, tbh, imho).
This reminds me of John McWhorter’s observations about lol and hey as discourse particles: he describes “lol” as marking empathy and “hey” as a topic shift. I’d say that the other current abbreviations like tbh, imo/imho, iirc, idk/idek, omg/omgz, wtf, etc. can have a similar type of function in marking the attitude of the speaker (well, writer) towards a particular idea.
Notice how the same statement (chosen to sound pragmatically appropriate in an informal, tumblr-like context) has a very different illocutionary force when accompanied by different markers.
(1) tbh they’d make a terrible couple. (certain knowledge)
(2) imo they’d make a terrible couple. (belief)
(3) iirc they made a terrible couple. (uncertain memory)
(4) idk they’d make a terrible couple. (uncertain, disbelief)
(5) omg they’d make a terrible couple. (strong emotion, excitement)
(6) wtf they’d make a terrible couple. (strong emotion, disbelief)
(7) lol they’d make a terrible couple. (empathy)
Perhaps this is the closest that English will get to having a system of evidentials…