There was actually almost exactly this debate brought to Mastodon by entomologists posting about their scientific research, much of which involved the public education of people who by-and-large live in a society where insects (and wider "bugs") are seen purely as disgusting pests - and they wished to discuss the beautiful creatures they were studying in light of the need to normalize this common part of our ecosystem
They were, of course, largely chased off Mastodon, or science instances were added to mute lists, because there were a lot of people who felt their particular phobic triggers should take cultural precidence and indeed that it should be normalized to hide insects (a category of life currently undergoing a mass-extinction event all aorund us) instead of showing them to the public.
I am a clinically recovered arcahnaphobe, so I don't exactly have an even-handed say in this mess. But my short version of it is: This is a bad idea, a bad practice, and indeed users tag muffling their personal triggers is what the cultural norm should be. CW'ing a common form of life that is necessary and integral to basically every thriving above-water ecosystem on the planet is not great! And spiders are part of that too!
We don't have a correct answer here because we do have friends and partners who are genuinely arachnophobic but man the way society treats arthropods and invertebrates as a whole as disgusting monsters that should be killed is so fucked. we remember on Twitter there was discourse for a while because someone posted their pet centipede and a bunch of people responded with "kill it with fire!" gifs and variations of. And that was someone's pet! Random strangers were threatening someone's pet because all they could see was a monster.
I think overall tagging and being able to muffle by tag is a much better solution for most potentially triggering content that affects a subset of users, and at this point it is one of the things that I think Cohost does quite well as compared to Mastodon in particular.
It's by no means perfect, and I think that the ideal solution would include some ability to granularly control post visibility and/or tag visibility, because right now, tags are used extensively both for discoverability and for content filtering, and that if you don't want your post to be discoverable, you have to use a full CW instead of just tagging it. (AND you also can't use common tags to be able to find your own stuff later without it being discoverable under those tags.)
