JasonC3 said: "Seriously?
"Who?" is a common retort when someone mentioned is unfamiliar to (or not seen as very noteworthy by) the person making the comment. It usually is not meant literally since anyone could Google the name as you note.
It has been used here many times by many people over the years, often accompanied by the Mariah Carey meme GIF. And comments that some construe as snark fuels much of these threads."
So you correctly identify what the word "who" means, but you put the lame snarkiness in parentheses: if you dont know who Alex Edelman is, cool! Its impossible to post on this site without being simultaneously able to figure out who he is within a matter or seconds.
So here "who" meant "thats not even someone whose name I, random commenter on a message board, recognize!" Hence the well-deserved snarky response, because either this person has some personal beef with Alex Edelman that they should work out elsewhere, OR they just want everyone to know how not-famous-enough Alex Edelman is (as his hit show embarks on its 7th or 8th engagement...) Y
our faux-confused reaction to this snarky stupidity is not much better.