It sounds as if the problem here is that it takes you time to write a detailed response after you've analysed the suggestion. That sounds like a job that GPT would actually be good at. So ask ChatGPT for a non-technical explanation of why the proposal won't work.

This way you're not discouraging people making suggestions, you're still considering the actual suggestion, and you've satisfied them that the technical solution proposed by GPT isn't valid, without wasting much time.

You could even add something like "I asked ChatGPT to explain why this won't work" to protect yourself from the inevitable errors.

It sounds as if the problem here is that it takes you time to write a detailed response after you've analysed the suggestion. You'll still have to do that analysis, but producing a plausible explanation for why it won't work sounds like a job that GPT would actually be good at.

Ask ChatGPT for a non-technical explanation of why the proposal won't work.

This way you're not discouraging people making suggestions, you're still considering the actual suggestion, and you've satisfied them that the technical solution proposed by GPT isn't valid, without wasting much time.

You could even add something like "I asked ChatGPT to explain why this won't work" to protect yourself from the inevitable errors. You know it means "this is probably wrong" but they'll probably read it as "this authority agrees with me".