USDT had a shady past and this came to the masses because they are centralized, what if usdt was a decentralized stable coin in the beginning will we ever know their shady secret? My point is its easier to hide behind decentralization and still commit crimes, all in the name of anonymity and decentralization crimes will be easy in crypto space, centralisation won't fix much either but with centralisation going deep into investigation is possible, facing the law is possible, oh regulation is 100% effective on centralised projects too.
First, think of it this way, if they were completely decentralized, then they would have have no crime to commit in the first place, and because there is no crime to commit, there would have been no shady secret.
Understand that decentralization means decentralization, there is no thing as partiality in it, if a company claims they are decentralized and still have control over one ot two important affairs of the company, then they are not decentralized, take bitcoin as an example, Satoshi Nakamoto invented bitcoin(blockchain) which gave birth to cryptocurrencies in general today, and yet, Satoshi has no control over any affairs concerning bitcoin, not even its network maintenance, that's true decentralization.
Many crypto companies Today know this but will still lie to their investors claiming they are decentralized meanwhile they are not.
If tether as a company was completely decentralized like I've said before, there wouldn't have been any means for them to commit the crimes they are being accused of, because they would not have had any access or control over usdt.