My problem with most herbal "remedies" is they don't say what's in them. They "support the immune system", hmm, so they do actually kill anything? Hard to say...they don't claim that & don't need to.
Things like Stress Coat have aloe vera that slimes up the fish in hopes that external parasites can't get into or onto the fish's skin or gills... if they aren't there already. Other "people" herbal tx can have issues too. Oregano oil has interesting properties but the LD 50 is very low (that's the dose that kills 50% of the test animals). There are many natural products, they aren't tested for efficacy or dosage; since they can't be patented companies go for "proprietary" mixtures...We just have to guess what's in them & if they work in fish.
I don't think a short round of salt or other "fish" med. treatment is unsafe for most plants or most fish, but maybe for some inverts. I forget what I was treating (not ich) for but my plants, pond snails & so called scaleless fish (corys &/or loaches) didn't seem harmed in any way. This short term use is much different than people who use "aquarium salt" on a regular basis. Often the salt issue is really a sharp rise in TDS. Many of our fish, plants & inverts survive in, maybe not brackish water, but with some ocean salts washed into their habitats by seasonal tides or mineral salts seasonally during low water times.
ALL treatments come with risks, so does doing nothing...
2 of the ingredients in "Kim's med" are known by California to cause cancer...I don't think if salt or dyes are used for 2 or 3 weeks to treat ich we are endangering either our fish or ourselves...in CA lots of things have issues, lol.
Like I said before I have not had to treat ich in many (many) years. I study my fish for quite a while before buying & quarantine for 4 weeks almost always, except for fish from fellow hobbyists I trust. I know not everyone can do that. But I also don't believe in hitting fish with every drug available "just in case" if I can't tell what's likely wrong, if anything. I like to have a good idea of what I treating for & make an informed decision I how I treat it. The only exception is treating botia-type loaches for internal parasites, but I haven't done that for 10+ years either...no new botiids for me lately, sniff.
OK, that's my herbal rant... again for now...