This statement is essentially a post hoc ergo propter hoc fallacy.
Anything that didn't leave you wiser after six years would be a pretty terrible way to spend time. Heck, simply being alive for six years probably makes you somewhat wiser.
No, it's not.
A post hoc ergo propter hoc fallacy is to assert that X causes Y _solely_ because X and Y co-occur. Philip asserts that doing the Ph.D. caused him to be wiser, savvier, etc, but he did so on grounds other than just citing their co-occurrence. Much of the rest of the article explained _how_ X caused Y, i.e., how doing the degree resulted in this or that bit of wisdom.
On a broader note, it really bogs down a discussion to point out 'logical fallacies' when they aren't there. Ideally, we'd all go out of our way to try to see another person's point, even when it's poorly made, but the antithesis of that is to criticize a point on technical grounds, when those technical grounds aren't even there.
also, that's sort of why i had the parenthetical following that statement ...
(Two obvious caveats: Not every Ph.D. student received these benefits—many grew jaded and burned-out from their struggles. Also, lots of people cultivate these positive traits without going through a Ph.D. program.)
I understand the grind as a tool for personal sharpening better than a successful graduate would because it is all I have to take from the experience - no plaudits, no social or familial approval, no resume bullet (rather more like a gaping resume maw, depending upon the attitude of the person reading it).
I have no idea -- that's why I put that parenthetical caveat in that paragraph :)
I can't speak directly for pgbovine, but I had a similar experience as in his book (finished fall 2011). I also can't compare to your situation since I don't know you. But I share pgbovine's sentiment: The PhD wasn't necessarily fun, but it was personally fulfilling. It also left me with a deep sense of accomplishment and appreciation for "just how far the rabbit hole goes." I often describe research as: 80% banging head against a wall, 10% cursing, 10% progress.
Some of my recent work is more akin to "engineering consulting." I've found this job to be vastly different from research -- implementing solutions that are mostly-known rather than exploring uncharted territory. It's probably closer to 30% banging head on a wall and 70% progress, without any cursing (and saner hours with better pay). YMMV.