After reading the post a few times, I gathered that you get all 3 bonuses even with 1 point in, but at different scaling. Example:
(these are rough and made up but its just to get the point across)
26/50 Holy Priest
Healing - Increases your healing by 53%
Meditation - Increases your mana regen from Spirit in combat by 53%
Radiance - Adds a Hot Component that heals 53% of the main heal over time.
Healing - Increases your healing by 18%
Meditation - Increases your mana regen from Spirit in combat by 18%
Absorption - Increases dmg absorbed by PW:S by 18%
50/26 Disc Priests
Healing: 18% Increase
Meditation: 18% mana regen increases from Spirit
Radiance: 18% of the Heal will be done as a HoT
Healing: 53% Increase
Meditation: 53% Increase
Absorption: 53% more dmg absorbed by PW:S
Now the numbers will scale differently and it won't be so linear, so for example 26 points will only equate to 15% bonus, or something. This way, subspecing doesn't harm you very much versus going full 76 points into a tree. ya 76% healing increase is nice, but 65% increases plus a 15% radiance might turn out better healing in end game. Same goes for the Mediatation mastery. I'll re-read the post but from the way it was worded, this is how I see it working. Also, they don't have to be necessarily the same scaling. For example you could probably get 22% healing if you put 26 points into Holy and only 13% healing by putting points into Disc, or vice versa. It will probably be scaled based on the way the spec works and the talents you get in the tree.
So I don't think going full 76 points into a tree would be as beneficial as going say 51/25 or something.