Also trust in PCR cyclers ist often low... PCR is often not straight forward, chemicals can go bad, primers don't work reliably, input DNA has inhibitors, etc. So people are quick to blame the thermocycler if things don't work for an unknown reason, or some have their favorite cycler that "always works for me", and don't what to switch to an unknown one. I guess part of the reason is that there is no log where you can check the exact temperature in every well of the block after the run. Failed PCRs cost money and especially time, so I can see why people don't want to try machines some guy built in his garage.