…allow me to note some of the posts which have had significant changes (as reflected by thanks in the comments) to initial text which had a serious effect to the tone of the piece without the author acknowledging an edit.

Since this (initially) seeming contradiction confused me at first, allow me to clarify what I thing you mean:

without the author acknowledging an edit [in the main body of the post rather than just in the comments].

That said, I agree that it would be better that they also acknowledge it in the main body of the post. However, at least they are acknowledging it in the comments!

In response to a comment:

No, the author of the initial blog post is often not acknowledging anything. What I refer to is many commenters objecting to some particular text in the copy of the initial post, and then later in the comment log those commenters thank the author for changing the initial text.

So, let me paint you a picture of what the late reader of a post sees. Assume the post has been edited to be reasonable. This hypothetical late reader then:

1. Reads a reasonable post,
2. Scans through the first few comments and sees that lots of people are objecting to whatever (the headline, the bias of the text, the inclusion or exclusion of a quote, etc.).
3. Finds no objection him or herself to the post (because it's already been edited), and leaves that post with the conclusion that the commenters are over-the-top in their objections.
4. Can not reach a conclusion about the slant of a particular blogger (gasp! bloggers have their own bias?) because all the data is not available to them

Who knows how many posts may exist that have been edited after their initial post because of commenters objecting but now can never be pinpointed because those commenters never bothered to thank the original author for a subsequent edit.