Text doesn't usually benefit from bold or italics just because it's technical specs, or proper names. Headings (i.e., section titles within an answer) benefit from bold but this is taken care of automatically when you make them headings by starting them off with
# markdown (depending on how big you want it to appear).
So you're probably right about these edits not being very good... but to know for sure, I think you'd have to link to some examples.
This is not to say that bold and italics cannot be used for good purposes. I use them in many of my answers, and while I think I may have occasionally gone overboard with them, for the most part I think I've used them well.
One purpose of bold is to call attention to particularly important points. Another is to help people navigate through the post or know what part of it they may want to come back to later. Remember, Ask Ubuntu doesn't facilitate linking to a particular part of a single post. When bold (or italics) helps express the logic or structure an author is trying to convey, and when it compliments good writing rather than substituting for it, it can be a very good thing. And some edits that add bold are good, too.
But I have also seen edits adding bold and italics, where my reaction is similar to yours, and I wonder if there's really any benefit.
Occasionally I've edited a post to put something in bold (while making no, or hardly any, other edits). I don't do this often, and when I do it's been to highlight something that's leading some people to seriously misunderstand the post. Most of the times I've done this, it's been for short but potentially valuable answers getting flagged as not-an-answer by reviewers not reading them carefully enough to see they really do say what to do to solve the problem. (When a post is genuinely unclear but can be improved through editing, a rewording is better. But when people are just misunderstanding it, a bit of bold can help sometimes.)
You're right that if a suggested edit doesn't really make a post more readable and does not otherwise add anything to it, it's not a good edit. The best thing to do when reviewing such an edit is to reject it.
Regarding your point at the end about answer quality: I don't know if overuse or non-helpful use of bold is actually leading to poorer reading of questions and worse answers. My guess is that if it is, it's only doing so a very little bit. But either way, if an edit doesn't make a post better at all, it's not a good edit.