Per https://musicbrainz.org/doc/Style/Artist#Name an artist that uses several different name variations should all be merged into the same MusicBrainz Artist when there isn't clear evidence they are different projects.  The current relationship editor in beta no longer allows crediting an artist using the default name.  This creates ambiguity, especially in Japanese artists, where they may change the script used to write their name to indicate different styles of music.  It also prevents future-proofing the credits on recordings/works/releases from artist name changes.