But "teleporters" or "marathoners" or tons of other words follow the same pattern of stress and sound fine. "Photocopiers" extends it to four unstressed syllables and sounds fine.
We treat words like they have a single stressed syllable and everything else is unstressed, and that's a useful abstraction sometimes, but that's not actually true. "Photocopiers" has primary stress on the first syllable but secondary on the third - PHO-to-CO-pi-ers. The same goes for "teleporters" and "marathoners".
But that also goes for "octopuses", so what gives? Seems like there's something else going on that my brain hasn't accounted for yet. It's probably that the plosives (stop consonants) are hugely unbalanced, with all of them coming in the first half of the word. Plosives, as the word implies, can add quite a bit of oomph to a word, even if they aren't reflected in the stress pattern. So "octopuses" seems to just peter out halfway through the word.