I guess if you found yourself next to someone who logged on for 12 hours straight everyday eliminating them would be easy enough. The greater likelihood is they would use alerts and have some reserve time to respond if necessary.
How would you find the balance? If all it requires is logging out when I'm not doing something, I can easily make top 10 and still not worry by doing that. If I have 12 hours to play, all I do is login and do my stuff then logout. Could still do very much very easily.
Either way, my main point was that you would essentially force a player to be online 12 hours straight and then they couldn't defend
. I don't know if you've been in a large war, but when you have 6,000 incomings they are landing fairly constantly and you have to dodge and watch out for noble trains quite often. Which means mostly continuous play if the enemy is any good. What then? I can't even have an account sitter to help me while I sleep like I usually would. All tribes would just do this, then it's just a game of "who can do this the most often and recruit members most to make up for it", rather than really fighting it out and seeing how much teamwork a tribe can have with an account under pressure.