I get the feeling some folks are getting defensive over this topic, when there's really no reason to. As already stated, there is no one size fits all, and clearly some hobbyists have figured out what works for them over the years.
The reason that I wave a warning flag is for those who have no idea what they are doing, either through inexperience, or just a fundamental lack of understanding the subject. There is nothing wrong with being careful, and taking precautions when needed.
Also, as I have already mentioned, disinfectant values can change over the years. For many years our little city ran on a lower residual of chlorine only, then one day they completed a major upgrade to their facility and switched to chloramine. With high pH values here that became important, as ammonia toxicity became a very real concern. Especially for those of us that perform very large water changes.
When chloramine tap water is treated with products such as Prime, Safe, the chlorine/ammonia bond is broken, resulting in a certain amount of free ammonia (NH3) that needs to be bound or reduced into a safe nontoxic form. The toxicity of free ammonia is highly dependent on both temperature, and pH, so this can vary GREATLY from one hobbyists tank to another.
A good read on the toxicity of ammonia and fish can be found in the following article posted on the krib.
http://www.thekrib.com/Chemistry/ammonia-toxicity.html
Experiments have shown that the lethal concentration for a variety of fish species ranges from 0.2 to 2.0 ppm.
Experiments have also shown that exposure to un-ionized ammonia concentrations as low as 0.002 ppm for six weeks causes hyperplasia of gill lining in salmon fingerlings and may lead to bacterial gill disease. At higher levels (>0.1 ppm NH3) even relatively short exposures can lead to skin, eye, and gill damage in some species.
Obviously free ammonia (NH3 ) is toxic to fish. How long that toxin will remain in one’s tank, and how toxic it will be, will be dependent on a number of factors. Temperature of water, pH value of water, planted tank vs non-planted, size of biological filtration, whether the biological filters are well established, or not, size/volume of water change, species and age of fish, etc.
IMO NH3 is very much along the same line as second hand smoke, something that my generation ignored for several decades.