How important is ph?

There is some bad info going around this board claiming that ph isn't important when it comes to growing. I would like everyone's opinion on this subject please (apparently I don't know a damn thing).

did i say it was emportant no.... i just dont think some one who is growin they first second third crop with only 2-3 plants under low powered lights a real necity... but some one who is growin on a commerical scale or who are growin show style plants this changes then it is important....

un-importment is was i meant in the first line

What are these spots? Why is my plant burned?
No P.H isn't a factor. If your a F*CKIN Idiot. Who are these Dumb asses. Do they use Incandescent lighting to with Tin foil and an air tight box.

Well my only experience was this:

My current grow Im into with WW and NL at the very beginning of veg stage my plants wouldn't grow. I did some research and one of the first things I came across was "Am I testing for PH"? Well at the time I wasn't. I just used water from faucet and that was it. I decided to see if the PH in fact could have caused no growth. I am totally convinced PH is very important in indoor growing, for as soon as i started testing my ph and keeping it regulated my plants took off.