It has some niche use(r)s. I for one use it daily - My preferred keyboard layout is US Dvorak, but as a noggie I sometimes need to type æøåÆØÅ, so I use compose for those, as well as the occasional trademark, copyright, degrees, etc.
You forgot interrobang‽ The most important and incredulous reason for a compose key.
It has some niche use(r)s. I for one use it daily - My preferred keyboard layout is US Dvorak, but as a noggie I sometimes need to type æøåÆØÅ, so I use compose for those, as well as the occasional trademark, copyright, degrees, etc.
You forgot interrobang‽ The most important and incredulous reason for a compose key.