Perhaps it is not incompetence that's the issue and more that they need such overwhelmingly undeniable evidence of cheating/illicit activity that they simply aren't willing to ban the vast majority of bots.

There was a noticeable increase in the number of bans during the week of the second Ishgard Restoration rankings where the Diadem bots had gone mainstream, but were prone to glitching out and getting stuck on terrain or in an endless loop of mounting/dismounting. People actually got removed from the rankings for cheating then, but come the third ranking session the bots had been refined, were no longer glitching out, and the number of bans remained as low as always.