Clown fish hosted by anemones or corals, good and bad!

Yes clown fish living in corals will kill them prematurely, but no great problem in the short term.
Think of it like the clown fish does!
If it is not at threat in the tank, it does not need a stinging anemone, so corals have far less intensity to their stings, though corals and anems are the same thing, one evolved algae to enable its cal skeleton and for just an extra food source, both uses algae for colouration and additional food source.
The clowns instincts tell it to use some thing at times, so the corals is the easier option, then of course the coral is toxic to it over time, the anem is not! Clowns to live long term in what ever anemone or coral, has to consume the anemone or corals mucus to mimic it and expel the copied mucus through its pores so the hosting coral or anemone will not know it is there, so it is not stung and killed.
With corals, there are toxins going in that they are not able to survive, in the long term!!!!