Does the community here consider HN as plaintext? Obviously, the site is html with hyperlinks etc ... but it's basically implementing a text interface that I c

Does the community here consider HN as plaintext? Obviously, the site is html with hyperlinks etc ... but it's basically implementing a text interface that I can click on. In a cryptographic sense, html itself is plaintext since it is encoded as ascii/utf-8. However, the MIME type of text/plain is distinct from text/html to describe the html encoding of document style/structure information. A terminal is often considered plaintext but in reality there are escape sequences to encode meta-information which is otherwise unreadable to most humans. On the other end of the spectrum, there are images with a few words transcribed on a lot of social media platforms. To blur this line, recent(ish) mobile platforms recognize text embedded in images and make it selectable. Given this context, is text in an image without anything else considered plaintext? I guess my real question is, "where do we draw the line" for what we call plaintext, decades after the initial implementation.