Chatbots and machines programmed to show feeling responses are mimicry. People can be tricked. If you want to fool ships with a fake iceberg, you won't bother with more than the tip. But if you're a glaciologist, examples of sailors getting spooked by fake plastic iceberg tips would not lead you to question whether natural icy marine bodies (especially ones that usually develop into icebergs!) have any mass below sea-level. Or if you're studying carcinization, the fact that robot crab decoys can pass for real tells you exactly nothing about why unrelated phylogenetic lines independently develop crab-like features.
And the "people" in "dead people" refers to real people, who die. A corpse is a "dead person" like a puddle of water is "melted ice". Mourning, including respectful treatment of remains, is symbolic. None of that is anthropomorphism.
It is established that human babies develop into human adults. Their pain and other distinctly human responses resemble the adult forms profoundly. Are babies "a system [that] responds to painful stimulus" but feels no pain? Occam's Razor says no. I see zero downside to reckoning that possibility out of the moral calculus.