I'm not making some sort of "invisible connection." It's informal logic. There is indeed a hidden implication in the statement "4E is not D&D," regardless of whether it's intentional or not. As I said, "4E is not D&D" is a plain-and-simple categorical statement. There is no statement of feeling or personal preference in that statement. There's no more implication of "what they feel" in the aforementioned statement than there is in "a fish is not a bird." Therefore, the statement "4E is not D&D" does indeed categorically imply that those playing (and by extension, enjoying) 4E are not playing "D&D," as it falls outside of the category of "what is D&D." You may not think of it as an "attack," but it is at the least unintentionally insulting to those who do see and enjoy 4E as legitimate D&D. But you can change all that by simply adding a subjective qualifier that does indicate that you are stating an opinion and your personal preference, as opposed to a categorical statement.
Not everyone speaks (posts in a forum) uses the clearest language. To those who try to be succinct and exact in their use of terms, as both and you and seem to share - not everyone have those skills. This is not a court of law, statements may or may not precisely match your or my reading of a given statement.
Saying X is not X, should not automatically carry any additional unsaid statements. If it's not clearly stated, one cannot assume it has some greater meaning.
To do so, is simply putting words into peoples mouths.
If someone states clearly that X game is not X, and anyone is playing X is really playing Y. Then, Hell yes, the person stating such thing would be saying something insulting and would deservedly get your retort. I'm behind you on that.
But without additional explanation from the person stating "4e is not D&D" in what he really means - I can't put words in his mouth, and 'finish their sentence', as I don't really know what they mean. Not everyone's logic is sound.
I'm just thinking your assumed 'insight' on what they are stating, might be mistaken.
Edit: and to the arguments that a fish is not a bird, is silly. While 1e, 2e, 3x, and even 4e share some elements, class names, some kind save mechanic, etc. We must all agree that there are differences in all those editions. Yet, most, call all of them D&D even though they are definitely not identical. What is called a fish, by any other name is still a fish. However a game is more ephemeral than that. Not everyone shares the same definition of terms.
To some people anything with the name D&D on the cover is D&D, I think that's your belief and a sound one.
To some people D&D is any kind of fantasy based RPG with fighter, magic-user, elf, dwarf - which includes many, many games that don't have the words D&D anywhere on it. (Pathfinder, C&C, HARP, BECMI, etc.)
To some people AD&D 1st or 2nd edition is the only D&D, and anything else is a different game.
If we all shared the same definition of terms and the same sound logical arguments, then assumptions could possibly be drawn. This isn't the case, so filling in the blanks on someone else's statement is irresponsible. We can't possibly know what any given person's statement truly means without clear clarification. For many members here, English isn't their primary language.