I find comments that start off like that extremely disingenuous. Whenever someone says "I <some adjective>, but..." I see that as "I don't want to offend anyone reading this because I don't want to get into an argument and/or don't want downvotes, but I'm going to say this anyway because this is how I really feel." Things like "I'm sorry, but...", "I hate to tell you this, but..." or "This is a great idea, but..." sometimes (emphasis on sometimes) have good intentions (like pointing out flaws in a website or bringing up an interesting point in the topic) but to me they end up sounding quite pompous and, in this case, offensive.
"All colors are made of light, but black is the absence of light."
"It looks like you covered all of the key issues, but you missed this one..."
"I agree with everything you said but this one thing..."
"I am not a lawyer, but it looks like it could be interpreted..."
I think you guys are just making these rules up, but maybe it is still good to keep them in mind, even if they aren't always true.
