The other issue with a wire nut is that if the wire gets a lot of handling, a wire nut can get snagged as the wire is wound and unwound. In this case, the cable runs to my portable solar panel -- I will be handling the cable a lot, deploying and un-deploying whenever I change campsites. A bulky wire nut would get a lot of rough handling.
Yes, tape would protect the connection, but it would still be a big fat bundle on each end of my cable.
For a stationary and well-protected application (like a wire inside a cabinet), a wire nut would be perfectly adequate.
