@mib2berlin makes sense to me if the unique selling point is a search database which is synced between devices. So regardless of which client has seen the full email body, every synced client finds / filters the email appropriately without necessarily having downloaded the message body.
I think this would be a great feature for cars in particular.
Today with the new version, I eagerly opened the release blog hoping I'll find this in there, but alas, I was saddened once again 😞 And so I thus refresh this thread once more, with an optimistic prospect it catches an eye of more supporters and may be, just may be, one day even a developer 🙂
@doctorg: Vivaldi on mobile doesn't have Reader View. Where it detects a web page with a more desktop oriented layout it asks "Do you want to use Simplified View". This comes from the underlying Google Chromium browser and presents a view that still shows adverts. Reader View on desktop is different and strips out everything apart from the article text and images.