These people know their stuff. it’s true that every time you cut a leaf mechanically (as with powdered teabag teas that you might buy in a supermarket) that the leaf oxidises and loses nutritional value with every cut.
But Matcha is not Cut. It is ground into a very fine powder, the leaf therefore is not broken in the same way, you ingest the entire leaf and get much more nutritional value because of this.
Matcha is precious because of the fine nature of its powder. For those interested in specifics, Matcha fineness can reach 1000 meshes (equivalent to about 8/10000 micrometer).
It is using an ultra-fine grinding process, which does not destroy the tea chlorophyll, protein, amino acids and other essential dozens of trace elements.
The ultra-fine nature of this form of green tea can also promote nutrient absorption. Scientific discovery has shown that with Matcha and other tea powders, when the particle size is smaller, it is easier for the body to absorb the nutrients. It is only in this form, that the true properties and benefits of the green tea-leaf can be fully realized.