Necro-ing this because a year and a half later and this is still not a thing.
We do have the option to use tab for that in the configurations... Only it doesn't work.
Opera advertises itself as the "Fastest, safest and smartest" browser... Yet, Chrome is currently ahead of it in the "fast" and "smart" aspects, in this particular feature. And considering this pops back up every now and then since 2016, I honestly think it would be very nice to see it getting implemented.