It seems potentially very useful for those with various types of executive dysfunction or mental illnesses that prevent them from either bodily or environmental introspection. If you have experienced these levels of dysfunctions or panics then you'll hopefully understand how a mindful and procedural reflection on your current state and surroundings can be very useful, and can let you escape from attacks, flare-ups or endless cognitive loops. Being prompted by such questions helps. For me, after a brain injury, I found it very useful, when in a panic attack, to step through possible issues and try to alleviate them one by one. Any marginal improvement is worth it if it helps you escape distress.

Also, some people have problems finding internal ways to articulate feelings. Emotional wheels (google it!) are very useful in those who are perhaps neuro-divergent and less able to differentiate internal states without prompts.

Of course a website like this is not exhaustive or entirely encompassing all experiences. But that doesn't necessarily reduce its utility.