Unfortunately it isn't that simple. Many strains of ich are now resistant to high temperatures and you need to go over 90 to kill them - something most fish won't tolerate. Salt, obviously, also cannot be used with scaless fish effectively and considering the popularity of plecos, cories and loaches, I'm sure it's obvious why such treatments can be difficult to use on your average tank. In most situations, you can try to use natural methods and they may not cause any 'ill effects' but that doesn't mean they will work. There's no reason to subject fish to the stress of a major temperature fluctuation or change in salanity when there are perfectly good medications on the market that also have no ill effects but will work quickly and effectively. Just my opinion.
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