Tiberius stopped the continual expansion of Rome, which was a good start. He was not up to Augustus’ abilities but aside from maybe five or so other Emperors, who was?
Tiberius had learned all too well in practice what Machiavelli would later write, it is better to be feared than loved
Were some of the families he destroyed an over reach, sure, but it was his head that was at risk. There was no planned succession, after he died, a free for all was quite possible. Getting rid of potential plotters or just encouraging fear may have been his only way to survive.
Noblesse Oblique just did not exist in his world.