Read every post; and I have to say- this was the greatest planted tank thread I've ever read! Mainly due to the heated expert arguments. And both sides here appear to be right...
Whomever posted that 'adding C02 to aquariums...' is the most prevalent search in google got my attention, however, searches using ‘adding better lighting’ and ‘good substrates’ appear to be more intuitive, and maybe this is why these terms don't get more attention. Adding good lighting seems pretty clear to most people, and does not need much research. Yet, when one is more serious about plant growth, and after spending a couple hundred on a good lighting system, they start to research more complex topics, like adding C02.
That said, the critics of adding C02 as being the complete panacea are also right… there more important considerations to make, such as ‘adding good light’ is far more important to the general hobbyist than adding C02. You can do almost as well if you are able to invest in good lighting.
For both sides that know far more than I do… well said!