You've reversed Cause and Effect. We know this because Fujito said so in October, during Freshly Picked. No one has Rank 10 yet.
Any person can edit BGWiki and very often a source isn't attributed in many circumstances. We know that Rank 10 yields +30 to all stats not because a player has independently verified them, but because Director Fujito said so in October, before the item's release.
So not only did they go against what they originally said (and even put in the game manual) about mastery rank not affecting gameplay, they specifically publicized that fact? interesting.
I'm glad you're getting something from mastery rank, but that wasn't its original intended purpose. And they originally said and promised that it wouldn't have an effect on gameplay. But since they added an item with high stats (if you have high mastery rank), that's no longer true.
Wooo! Rank 9!! There are still quite a few weighty things I haven't done yet either like several more ranks of Chocobo Digging, ALL the Master Trials, any M50 jobs, and making an escutcheon, so it's bound to be possible...
I've done... well, quite a lot. I have over 970 titles, including some like Mimic Masher, and Triumphant Owner, I leveled every Monstrosity monster to 99, have Lu Shang's and Ebisu rods +1, capped out my synthing skills, and completed every side quest with only 1 subquest exception that doesn't appear in the log. I've also done every RoE quest with the exception of Sortie & Escutcheon RoE's.
I've played with monstrosity a fair bit, though I definitely haven't played everything. I probably should do more of that.
The Xhifut subquest from Peddlestox. Those parts are hard to come by (drop rate wise.)