When I first read "No need for stupid sarcasm, thanks.", I considered it a personal attack, a criticism of the individual making the comment and not a constructive criticism of the comment.
I suspect you do not have a good appreciation for what the word sarcasm means nor the implicit derision the word conveys.
A normal denotative meaning of sarcasm (according to New Lexicon Websters Dictionary 1990 edition) is "n. a cruel humorous statement or remark made with the intent of injuring the self-respect of the person to who it is addressed ...".
So, by labeling the comment as sarcasm (not matter the intent of the "stupid" qualifier) you made a value judgment of the speakers intent and character; and that being a negative one. Thus it would usually be seen as a personal attack on the speaker.
However, in my opinion, even the use of "stupid" in such discussions is sufficient to be offensive, especially as its secondary mean (from the same reference dictionary is "adj. ... resulting from lack of intelligence". And you appeared to understand this as you gave an excuse for your use of the adjective.