valid argument but its hard to believe bc even at their peak they were hardly selling over 50k while snsd at their peak was selling around 500k which is a pretty big difference. even while snsd were in their 10th year they were still selling over 100k. if the gap wasnt as big then i would say i agree with you.
I think it's safe to say that T-ARA could have been on SNSD's level, or a bit higher, but SNSD will have the longer longevity since they have the bigger fan base (which is the main driver for album sales) and general public; while T-ARA is heavily on the general public with a better than average fandom. By the way, T-ARA's best-selling album is Funky Town (with "Lovey-Dovey" as title) with almost 78K sales.
T-ARA could have had South Korea, Japan, China, three reputable idol actresses, and variety.
Oh well, it's still unfortunate to think about of what happened. They might be still active right now, uwu.