It's important to remember that:
* Anecdotes and stories can be exaggerated or fabricated over time. It's possible a story exists about someone criticizing Disney's imagination, but without solid evidence, it's hard to say for sure.
* Disney faced many challenges and rejections in his career. However, these were typically related to the business side of things or creative disagreements, not criticisms of his imagination.
While it's possible someone may have said something dismissive about Disney's ideas, it's unlikely to have been a significant event in his life, especially compared to his many successes and achievements.