I've stuck completely to this rule so far. Kids are now 10 and 12.
They do have their own "playroom" downstairs- where they have a TV, PlayStation and Nintendo, an old laptop for homework etc and tablets are kept here too (so I can keep an eye on what they are doing).
I really believe that their bedrooms should be electronic free zones and even made sure the WiFi signal doesn't reach that far.
My oldest is now telling me AIBU but I want to stick to my guns. They can have electronics (and I think they are very lucky in what they have) just not in their bedrooms.