Human-centered design emphasizes the use of AI-generated personas sparingly, if at all, due to ethical and practical concerns. While some UX researchers see synthetic users as a tool for efficiency, others view them as an unethical abomination. Synthetic users can be useful for simulating low-level artifacts in studies. However, their artificial nature raises questions about their ability to capture genuine human feedback. A significant challenge with AI personas is their tendency to be overly optimistic and agreeable. This "prompt-to-please" behavior can create a false sense of product satisfaction. A study found an AI persona named Alice was helpful but uncritically agreed with design proposals, lacking critical real-world considerations. Despite this, synthetic users can offer speed benefits in the preliminary stages of UX research. Their convenience lies in bypassing the time-consuming process of recruiting human participants. This makes them valuable for tasks like survey design and early-stage research, but not for final decision-making. Ultimately, human complexity, with its emotions and diverse experiences, remains irreplaceable in UX research. Synthetic users provide generic, plausible responses that lack genuine human insight and empathy. They are best utilized as a hypothesis-forming tool to inform initial ideas before human research begins. Synthetic users should only ever scale existing human UX research, never serve as its sole data source.