Yes, in that sense, I expressed a contradiction. Since the meme stifles
progress and free inquiry, it results in harm. Language is an imperfect
medium, English moreso, and my command of English below that. Let's
see if I can parry your jab here.
To be precise, let's put the meme this way: "Words which honestly
express ideas of a speaker may provoke unpleasant emotional reactions
in some listeners, and it is therefore advisable to not express those
ideas." The delimma of psychological causality does complicate matters,
but the nature of the bad meme is clear: the meme says shut up because
you might cause offense.
So the meme, then, must be attacked not because "words cause harm" is
objectively false, but because (1) is mislocates the harm: the listener's
emotional reaction is not "harm", it's just the way he is, and (2) it
prescribes the wrong remedy: silence, rather than tolerance.
Now the ways in which the meme is expressed are varied, but some variant
of "Don't say that, you'll hurt his feelings", or "If you can't say
something nice..." are common. The opposing meme, that a listener should
be tolerant, is found in expressions like "Sticks and stones..." I much
prefer the latter.