As it applies to homebrewing, the answer is the internet. Without it, about 5 people would know about keeping air out or the other thousand important things there is to know about making a decent beer. Just my opinion.
1000% this. even more than just the internet is the way the internet has become ubiquitous and super accessible for non-tech savvy people. its about crowdsharing/sourcing info, and with more and more people online (probably reached the kind of saturation i mean in the late 2000s, where forums like HBT had dozens if not hundreds of posts each day) and easy ability to post video files and detailed, HQ pics or even just link people to online purchases directly.
lol about the low O2 thing, i don't think there are many people here who disagree that in an absolutely perfect brewing system there would be flushing of oxygen from tubing, methods to reduce o2 on the hotside, etc.
it's just two things:
1. i and many others homebrew absolutely delicious beers that are really exciting to drink and hold up really well to some great quality craft commercial beers. so narziss worked at weihenstephan and i presume worked with other bavarian breweries? yeah i like their stuff, its not my favourite, but its good. so how can we prove that his o2 purging makes some mystical super beer? which beer do i buy to taste this supreme oxygen-free malt taste?
2. the o2 reduction steps would be another big pile of work to do and costs incurred and frankly i just don't care enough to do it. a lot of people do really embrace a simple homebrewing style.