I hate to break it to you but your wrong. Dr Tim's and ATM Colony and others have a very solid track record of working. I have used these products myself and cycled large tanks 75g in 5-7 days. If the products didn't work than how is this possible. Keep in mind filters new, new substrate, new tanks, new everything!
With that said these products require ammonia to be present so the bacterial can feed on. So it WILL NOT stop ammonia and nitrite levels. The idea is that with a limited stock (few fish) and limited feedings (once every 3-4 days) and keeping a close eye on parameters the fish will be me okay with a trace amount of ammonia and or nitrites for a few days in order to achieve the fully cycled tank.
This is why you should use a more known robust species to do this with, delicate species will still die with small amounts of nitrites or ammonia and should't be used.
Another HUGE problem with this situation is that MOST hobbyist who use these products are also putting fish right from the pet store in these newly setup tanks. Even a hard species like a danio or platy will have a struggle making it. WHY you ask? well because you are not taking a healthy prime specimen, but rather a weak stressed out fish that just went through hell to come home to a uncycled tank. With healthy stock you generally won't have any issues.
Also forgot to mention that for these products to work there is more to it than just pouring it in. PH should be 7.5-8 ideally and temps should remain close to 80f good flow is a must and there has to be some amount of ammonia present. make sure you check the expiration dates on the bottles as the do have a shelf life. The date doesn't mean its good either. The storage must be done correctly or else the bacteria dies in the bottle. Many variables here but if done right IT DOES WORK.
I will challenge anyone who wants to do a fast cycle without seeded media while using live stock right away. lets see who can beat me. I have done it several times in 5-7 days from nothing to a full cycle and NO DEAD FISH each time.