Why should I use alt-text?
Because people won't boost your images and they'll complain at you if you don't? Beyond being very rude to others, you deny yourself a wider audience by excluding people with visual difficulties.
Also people with limited reception appreciate this, and in many cases, the point of the meme may not be obvious to others.
You can clarify what _you_ think the point of the meme/cartoon is and avoid "Twit-terpretations" aka bad faith readings with alt-text.
5/T