1975. Playing
The empowerment given by Supreme Thief went far beyond the simple addition of techniques or memories. Wilfred and Steven had added important pieces to their existences, and they fit so well that they struggled to understand how they had managed to grow so much without them.
The techniques that Wilfred had learnt were only a practical application of a part of the cultivation journey that he had ignored for various reasons. The hybrid wasn't actually stupid, but his innate advantages and character had allowed him to grow without relying on special abilities.
That approach to the cultivation journey had initially been a mere decision that suited his existence. However, it had transformed into a proper limit that had prevented his power from evolving for a long time.