Mostly agree. It's really irritating and unproductive (and for me, all too frequent) when someone thinks they've got you nailed because they found a hidden assumption in your argument, but that assumption turns out to be completely uncontroversial, or irrelevant, or something your opponent relies on anyway.

Yes, people need to watch for the hidden assumptions they make, but they shouldn't point out the assumptions others make unless they can say why it's unreasonable and how its weakening would hurt the argument it's being used for. "You're assuming X!" is not, by itself, relevant counterargument.