Without any examples it's hard to tell how valid these complaints are. There are many great writers that depended on their editors to make their works better, but the label 'masterpiece' still belongs to the authors (think of Max Perkins' work.)

I'm sure Jane's (yes, I am on a first name basis with her in fact.) manuscripts were a mess. She didn't have the best writing tools even by the standards of her day, and clean copies of project in work were expensive and time consuming. Also, wouldn't it be hard to judge the spelling skill of someone before spelling conventions were standardized?

Poor punctuation tells us little about the nature of either a story or of a sentence. Yeah, I like them when I'm reading too, but hardly mess them when I hear some one speak, and a writer that thinks no more of commas while writing than they do while speaking doesn't lose the claim to being a great story teller, does she?

Besides punctuation conventions have changed a lot in the last two centuries. Dickens's and the Brontes' works have all been reedited for modern audiences, and enough commas have been removed for every Defoe or Swift work to have given Hemingway and Stein both a life time supply.

Maybe some editor just found a nugget of a tale in Austen's writings and rewrote them but, if so, why are there no other works by that genius? I'm not buying this at all.

[semi-obligatory Jane Austen related YouTube link]