Sorting an album list by composer is problematic because of multi-composer albums:
This is also why you can’t sort albums by Primary Artists — there may be many of them. Albums can be sorted by “Album Artist” which is a single piece of text, it may contain several artists but it is sorted as one item, by the first artist listed. The problem is that the metadata does not contain an entry for “Album Composer”. So there is no obvious answer for the album listed I included above.
I have asked for an album list sorted by Primary Artist, accepting that albums would be listed multiple times. If we had that, it would work for composers as well. But many consider such a listing disconcerting.
Of course, if the request is only for an album listing instead of a work listing under a composer, that is simpler.
But note that the results may be unexpected. I’m not a classical fan, so my focus on Benjamin Britten as a composer looks like this, which many would consider odd: