You're aware that beta carotene, which was hailed as a super food suplement before the term even existet turned out to be carcinogenic? Uups!
I'm not a food scientist, but believe it's extremely problematic to focus on one component or ingredient of something, which is a rather complex combination of a lot of ingredients in a product. Green tea extract may not act the same as actual green tea for umteen reasons.
Another point is cultural context. I'm convinced (and may be talking out of my arse, but I'm still convinced) that part of what makes something like the mediterrean diet successful is cultural context. People take the time to sit down to lunch and dinner. And this matters.
If you try to repackage the exact same ingredients and wolf it down in 10 minutes in front of a tv, or during lunch at your desk it's not the same thing and does not provide the same benefits.
You're free to put me down as some esotheric crank. But my conviction is that a healthy diet is a mixture of not too much crap and sometimes a bit crap, because it's fun and makes you feel good and gives you pleasure.
Nutrition, in my opinion, is much more complex than the ingredients that you put into your body.
https://www.ncbi.nlm.nih.gov/pubmed/30174618
https://www.ncbi.nlm.nih.gov/pubmed/29429153
https://www.ncbi.nlm.nih.gov/pubmed/28904061
https://www.ncbi.nlm.nih.gov/pubmed/28585735
https://www.ncbi.nlm.nih.gov/pubmed/27806972
https://www.ncbi.nlm.nih.gov/pubmed/27062963
etc.
Even studies with just "Green Tea" in their titles use green tea extracts: https://www.ncbi.nlm.nih.gov/pubmed/27797683
It's obvious that the public would not be interested in green tea without all the studies using concentrated green tea extracts.