Imho, part of this is an industry failure to provide an interoperable way to share documents that meets the needs of the modern web - a way to copy documents by-value instead of by-reference that runs in the browser, and can be composed into an existing website.
We made sharing images dead simple. You can copy and paste them around. Download them and upload them. You can copy the hyperlink and the target site can either display it by ref or it can copy the content and display it inline. On the modern web the copy/paste works amazing for images.
Text is similar - I mean, you can't load a .txt file into most comment boxes, but you can trivially copy and paste text.
Rich documents with inline images? Nope. If you copy and paste rich text data or HTML, the images are probably going to go away - Reddit's rich text editor fails on this. Raw markdown or HTML? Getting the images in is tricky, you generally need a parallel way to upload them and need to update all their paths separately. Copying and pasting rich text is always a roll of the dice about what's going to get mangled... for Reddit? It's images that get mangled.
That's why dumb screenshots have won. Because documents don't support dumb copy/paste usefully. I can't copy/paste a Tweet but I can screenshot it.
To add to your point: on Mobile, taking a Screenshot is also
1. Really easy
2. Uniform across Apps
I've noticed that college students don't really know how to use e-mail anymore, and they will send screenshots of e-mails instead of forwarding them. Kind of makes sense, though, when only some Apps have "forward" and each one has a different way to do it.
Why fuck around with that (or copy/paste, which is a nightmare on Mobile) when you can Screenshot.
Embedding gifs is getting harder as well. I wish I could spit in the cereal of whomever at Google decided videos need to show up in image search. Even when you search for a gif you saw fifteen years ago you have to sort through a dozen webm or gifv or mp4 versions of it before finding one you can actually embed with an [img] tag.
We made sharing images dead simple. You can copy and paste them around. Download them and upload them. You can copy the hyperlink and the target site can either display it by ref or it can copy the content and display it inline. On the modern web the copy/paste works amazing for images.
Text is similar - I mean, you can't load a .txt file into most comment boxes, but you can trivially copy and paste text.
Rich documents with inline images? Nope. If you copy and paste rich text data or HTML, the images are probably going to go away - Reddit's rich text editor fails on this. Raw markdown or HTML? Getting the images in is tricky, you generally need a parallel way to upload them and need to update all their paths separately. Copying and pasting rich text is always a roll of the dice about what's going to get mangled... for Reddit? It's images that get mangled.
That's why dumb screenshots have won. Because documents don't support dumb copy/paste usefully. I can't copy/paste a Tweet but I can screenshot it.
edit: This is also why gifs beat video.