think of it this way.....if youre driving your car and your fuel needle is on E, but the distance computer tells you that you have 200 miles of range, are you going to pull over for gas or keep going?........i think most of us would pull over and assume something is wrong with the computer.
buuuut if were on E and the computer says we have 10 miles, well probably assume we actually have 10 miles left of fuel.
i take the same approach to diving....ill plan my dive and get a baseline number, and ill try to dive more or less my plan and ill expect my dive computer to be more or less in the ballpark.
but if im at 100' and my computer is telling me i have 60 min NDL......im going to assume its faulty and stick to my planned dive time.
i feel computers are a safe and reliable method for timing recreational diving......but you are also responsible for your own safety, and responsible for knowing what you are doing.
just the same way as if someone drove into a lake because "their GPS said to" is not an excuse.......blowing a deco limit because your computer "said to" isnt an excuse.