Is it really that tough to make and install an inset cabinet door?

Granted, I've not yet done any inset cab doors, just overlay. Yet, I am
puzzled by the detailed article in the current FWW (176) on how to install
an inset cab door. It looks more like "How to fix a bad inset cab door
situation".

The author starts out saying, "As with any door fitting, the process is
easiest if the door and the opening are reasonably square and free of twist
to start with." That makes sense, even to me. He goes on to say, "I build
the doors just a hair (no more than 1/32 in.) larger than the case
opening." Considering that he wants a finished 1/32" gap all around, that
means he builds a door 3/32" too large and works down from there.

For those of you w/o the mag, the 6-page article and photos show him using
a TS sled to trim the bottom of a cab door at a very slight angle to fix
for square w/ the opening, using shims to determine how much needs to be
trimmed for size, and then trimming the other sides with a jointer and TS
for fit.

(BTW, did you ever think that maybe Formica started out as a shim company
and one day someone said, "Hey, y'know if we made this stuff in large
sheets maybe we could sell it for countertops."?)

Considering that the author says that he has hung "hundreds of inset
cabinet doors" and that his article is in FWW, I figure there may be
something to his methods. Yet, he seems quite clearly to be saying that he
cannot build a "square" cab opening and door. OTOH, that seems like a heck
of an admission. OTOH, I can imagine that even a small out-of-square on
the door or cab can make the gaps uneven -- and the key is the gaps.

Is it really this tough? Is this why most cabs have overlay doors? Is it
really good SOP to construct panel doors oversized? What about a
double-door cab?

I may have to rethink my new kitchen plans. Either that or start getting
in shape for lots of running up and down the stairs from the kitchen to the
basement shop. Comments solicited. TIA. -- Igor