Currently, when you ask your Google Home or Assistant to 'play [artist]' or 'play all songs by [artist]', or even 'shuffle [artist]', Spotify will respond by playing a curated playlist called 'This is [Artist]'. As an example, saying 'play all songs by Radiohead' will not actually play all of Radiohead's catalogue - only a selection of around 30 songs.
On its own, the 'This is Artist' selection is not inherently a bad idea, but it means that there is no way to specify that you want to hear all of an artist's catalogue.
When a user explicitly asks to shuffle an artist, or to play everything by an artist, Spotify should oblige, by playing everything that artist has to offer. Otherwise, I and my family have found that eventually you've heard all of the same songs in the 'This is [Artist]' playlist several times, to the point where it appears Spotify's selection is extremely limited.
Given the simplicity to implement this feature, as the Google Assistant will make a different callback when asked to shuffle an artist, this seems like a basic feature that is much needed.