Only person who's said that is you.Zurai said:
You want some mechanical formula that will spit out a perfectly-formed monster. That's never going to exist, because there are too many variables to consider. The DMG gives you a starting point. I wish it gave us more, as robertliguori also mentions, giving us an idea how to balance non-damage effects against the numbers in the DMG, but such is life. As is, it's perfectly fine for creating a regular damage-dealing-type monster from scratch.
As for monsters in the MM being a point or two off from what the process suggests they should be, there's no way to know why that is. It could be a typo in the defenses, it could be a typo in the ability scores, it could be something that emerged in playtesting (although that seems a bit doubtful WRT goblin brutes), it could be the monster used to be a different level and all the scores weren't updated properly when that was changed, it could be the monster had a different ability score and everything wasn't properly updated when that was changed. Since the monster stats are largely not formula-based, discrepencies like that are going to be pretty common and no one will ever be able to conclusively say there's a mistake. Much to the relief of game book editors everywhere, I'm sure...
