Is MusixTex easy and intuitive to learn? Because otherwise I feel like just using any sheet music software and taking a screenshot would be simpler/easier.

My upvote is for having some way to type music inline; I don't know anything about MusixTex in particular. For larger things I'd probably use music software and upload an image, but I imagine it will be useful sometimes to include a short bit to illustrate one particular thing (a harmonic pattern, a progression, a notation, etc), and it'd be nice to not have to do Encore -> screenshot/export -> upload for one measure. I don't know how much that'll happen in practice.

Why can't you post it as pictures?

@Lundin I certainly could; not everyone has access to music transcription software or is able to legibly handwrite sheet music.

@Quintec Admittedly MusixTex is fairly obtuse. If the design team pursues that avenue of approach, I would recommend simplifying some of the commands, similar to how MathJax simplifies many of the base LaTeX commands.

@DonielF Umm, you can buy blank sheets with lines and a pen fairly cheap. I'm far from having any form musical talent myself, but even I could draw simple music notes with pen & paper when I was around 10 years old. From there on just have to find someone with a smart phone to take a photo. I don't think providing free music sheet software is something Codidact should invest time & resources on.