I don’t know. If a medicine cures 99 % of all cases (or even 10 %) would you say it’s ineffective? I’d say it’s effective, but depending on the your overall goal, not effective enough (if you’d like to call it ineffective, it would be ineffective with respect to a certain macro outcome, not with respect to individual cases). At some minuscule percentage (let’s say 0,1 %) I would probably be tempted to actually starting to call it ineffective.