I think typically, the reason people are disclosing their usage of LLMs is that they want offload responsibility. To me it's important to see them taking responsibility for their words. You wouldn't blame Google for bad search results, would you? You can only blame the entity that you can actually influence.

Because if they'd actually read the output, then cross-checked it and developed some confidence in the opinion, they wouldn't put what they perceive as the most important part up front ("I used ChatGPT") - they'd put the conclusion.

Or, if you preface a comment with "I am not an expert, but...", it is not often about seeking to avoid all blame, but to simply give the reader reasonable context.

Of course, you are right, it is also sometimes just lazy dodging.

I find a good workaround is to just say "some very quick research of my own leads me to ...", and then summarize what ChatGPT said. Especially if you are using e.g. an LLM with search enabled, this is borderline almost literally true, but makes it clear you aren't just stating something completely on your own.

Of course, you should still actually verify the outputs. If you do, there is not much wrong with not mentioning using the LLM, since you've don't the most important thing anyway (not be lazy in your response). If you don't verify, you had better say that.