Question: I left a comment on [this answer](https://law.stackexchange.com/a/83285/11062) that is now gone and I am not sure why. My understanding was that comments are an appropriate place to offer points of view that differ from an answer so that future readers can make their own determination of the merits themselves. I had meant my comment to be a gentle statement that in the US, "checking the contract" might not apply to a laboratory/doctor relationship because those relationships are often totally unaffiliated (patients have legal right to take any particular order to any lab they choose). If my comment crossed some sort of line I would like to better understand that so I can avoid crossing it in the future.

Cheers,
M

Answer: 
Ref: <https://law.stackexchange.com/help/privileges/comment>

Comments are ephemeral. They can be deleted for any or no reason.

(In the case of the particular comment in the question here: it was flagged by the answer author as "no longer needed," and I, seeing no other reason to keep it, deleted it.)
Thank You comments are unnecessary
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Comments are to comment on the question or answer and request clarifications. Thank you comments are unnecessary. If you find something helpful: vote.

Commentary might be irrelevant
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I had written the answer you note. It is not relevant that most doctors are not the ordering party from the lab. The answer just points out that that **might** be a setup that exists, not that it is common. I did not see how your "but this constellation is uncommon" was relevant to the answer that is basically boiling down to "Read the contract and who is the party to the contract."

I read the comment, I saw nothing that I would want to add, so flagged "No longer needed" - as in "I saw this, ok, not gonna change anything."

Otherwise:
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[Comments are ephemeral.](https://law.meta.stackexchange.com/a/1515/10334)