Scrobbling to last.fm is a big part of listening to music for some people.
Spotify Connect should support scrobbling to last.fm (although I am not sure how it could be implemented!).
Updated on 2018-12-14
Thanks for sharing your thoughts on this idea in the Community.
We’re excited to announce that scrobbling with Connect is now implemented. If it's not working, head to the 'Apps' section on your Spotify account overview and disconnect Last.FM. Then head to Last.FM and reconnect to Spotify. This should help 😄