Pressure inside a traditional adjustable gas block is reduced by never allowing the excess gas in to begin with.
So this block diverts excess gas through an exhaust vent on the block. How is that better than diverting the excess gas through the end of the barrel? With this block you have the full amount of hot gas & contaminants (that can flow through the gas port in the barrel) entering the block & being routed to a vent opening with a metered portion being split off to the gas tube. Traditional adjustable blocks meter that same portion of gas to the gas tube & route the remaining gas down the barrel to vent out of the end without it ever entering the block to begin with.
How can this system run cleaner & cooler than a block that never allows the excess gas in to begin with? Maybe they mean cleaner & cooler than a non-adjustable gas block.