Popularity would make it very hard to manage. I couldn't even remember which ones I'd set as open. Unfortunately, you can't tag a list without tagging every word in it as well. Hopefully the marker feature will be out soon.
Not to mention, having it in my lists is somehow annoying.
I'm hoping John will add the promised automatic marker soon and this method will never become popular enough for me to have to worry about it. (Besides, the right-hand column would become enormous if we all used this...)
Just noticed the conversation about open lists on features. I'll add this word to all of my open lists in case anyone wants to add to them. (And thanks for all the help I've had so far!) Credit: Prolagus