I’m one of the 12.4K.
That’s mostly what I think, but maybe I’m just old. (I remember “You’re in a twisty maze a passages that all look the same” from Zork; I also learned Fortran on a DEC PDP-10—thankfully I was able to use terminals that printed on paper rather than punch cards).
I’ve seen people make compelling arguments that “liking” a sad post is inappropriate, and I have to agree. For me, though, I’m willing to assume that if someone “likes” my post it could indicate acknowledgement, agreement, I’m with you (in which case, a “like” for “my mom died” is just fine), as well as “I like what you posted”.
Mostly, I’m annoyed at the extra clicks that the reactions take, but am willing to put up with them because some people think they’re cute.
EDIT: But from now on, I’ll just choose the most absurd response and go with that. No more 
s for me. I think that 
may be my favorite. What on earth does it mean?