here's my thinking expressed in more detail. firstly I need to create the mixture, whether dry or wet. either way I have to measure the components and in terms of getting their ratios right, water doesn't help me there. then i need to make sure i know how much of the mixture to add to the tank, so at this point I have to measure out how much mixture to administer. again, whether there is water there or not does not help. so i never understood how water can somehow give you more control on your dosing. i mean if need to add 2 solvents together precisely, how does also adding water somehow make it more accurate?
another argument i heard is that it can help control the concentration of the mixture. but again you can just as easily achieve the same result by dosing less. so why even bother diluting? if i need to add two solvents together in a certain concentration, why would i add more and then dilute it back down with water? and anyway, i would also argue it's a bit pointless to be trying to exert that much control over your mixture because a) one can't measure plant intakes accurately to be able to predict with any certainty how much ferts should be used and b) ei is all about not worrying about this sort of thing anyway. i do find it a bit amusing that hobbyists adopt ei but spend all their time measuring out exact ratios and ppm to exactly target 25 or 30 ppm or whatvever arbitrary number they got from the web and using an autodoser to get even more precision.
the other arguments i have heard is that they harm the fish. well. the tank has water in it so it will be mixed in. okay, but perhaps some fish will eat some before it dissolves? well i've seen fish eat fresh poop and spit it out. poop has urea which i would argue is more harmful than kno3. in any case i have not read about fish falling sick because they happened to swallow some fert powder. there's lots about fish falling sick from too high nitrates or whatever in the water but that would happen whether you administer dry or wet. my own fish certainly don't seem to care what they put in their mouths.
another thing i heard is that autodosing is necessary if you go away, and that needs a solution. well, here's another secret. why not just add powder to your autofeeder? i tried this once - adding ferts with fish food in a feeder thinking it was a bad idea but the fish did not care at all and i have been doing it since. in fact now i always just use my feeder to autodose my ferts. that cost me just $10.