The reason why data reset will happen is because ABD Exploiters duplicated a large amount of shinies. For example, maybe your OMT (One more time) is duplicated. But it's still, they wipe out every player data just because of exploiting. Now, you will never see a OMT or MOHE. Since they were unobtainable stands, they won't be seen in-game. But it still fair. The devs needed to make this in order to make the trading balanced. Plus, nobody will end up victorious, It's everyone's data that will go. And, it's maybe a new way to introduce players to a new Stand. (Stand mastering.)
Just to be clear, It's NOT the development team fault.
In the end, data reset has pros and cons. It's a really "healthy" thing to make the trading on point. I hope all understand why Data reset is important. Cya.