The runes from eight inner gates work, the difference between the stats on the runes is the effectiveness of each stat. So for example the runes that gives Ninjutsu and Taijutsu are more effective than the runes that gives Ninjutsu *ion and Taijutsu *ion. The reason many believe certain stats don't work is because some stats require a much larger amount for it to show an observed effect. Hope that helps!!

Having no effect and having what is believed to be "no observable effect" are two different things. There are many factors that come to play but every stat does have an effect. Some just requires a much larger number to actually see an observable effect. That is why it is important for many people to use/upgrade stats that they believe are important or give the greatest effect. Not every stat is equal, it is up to the players to choose what they want to use. Some will choose to not use *ion because it doesn't give them the best benefit over other stats, that is again their choice =>

TLDR: Every stat does something, some stats just do more.