Playest texts are not usually edited or proof read as they literally change every week.
In terms of the armour:
Our version 1.5 launching soon uses the model that armour is situationally excellent. It has mail (no functional difference between chain and scale) and plate is Aquillonian plate. The point is not to historically model armour, but where REH mentions it, to include it in a way that feels right without getting in the way of story telling
Having been involved in over a dozen playtests of (mostly now published) professional materials, lack of spellcheck is NOT the standard.
FFG - three open betas, two closed. All spell checked, and well edited.
Green Ronin - the weekly drafts lacked significant spelling errors.
Far Future Enterprises - Spellchecked, laid out.
BTRC - all 5 materials I've playtested were consistently spellchecked. Everything was also laid out - and one of those was alpha.
Deep 7 - Alpha test materials spellchecked and well edited. Beta test looked almost identical to release sans art.
Amarillo Design Bureau - Alpha materials B&W, spellchecked, laid out clearnly in 2 col. Beta laid out to publication standard.
Mongoose - Spell checked and well organized. Weekly in alpha. May make lots of other screw-ups, but at least it's consistently spell checked.
SJGames - spell checked, and often laid out in two column.
I say, sir, if you don't meet the minimum standards in a public alpha, there is little to no reason to think you've anyone who CAN spell check it competently later. Which means basic computer literacy failures. (Learning to use spell check utility in a word processor is a basic skill. And given that spellchecking is far more a pain once one gets to using serious layout software... Did I mention I've done some publications work? No? Back in the late 90's, not in the gaming industry.)
Either that or simple inattention to basic communication skills. Again, not conducive to bothering further looks at the game.
Combine that with Gygaxian errors - your first impression is excessively amateurish. Defending non-spellchecked manuscripts looks even more inept.