It's plain old marketing tactics for the noob kids mate, whoever displays the largest number MUST OBVIOUSLY have the strongest shit? Erm........no.
See what they don't tell you is whether 29% of the total cannabinoid content is THC or the whole plant tissue is made up of 29% THC, if the plant tissue was made up of 29% THC (impossible) it would burst into flames as soon as a light went near it!
Then there's the physical amount of trichome coverage to take into account and this is different with every plant and grower, you could have a plant that produces a total cannabinoid content of 99.9% THC but if it doesn't get frosty then it's as good as useless.
Now do you see the irrelevance of it?