I fully support the idea of having some proper formatting options for highlighting. That is to say, the ability to add some background color, like blockquote does, but inline and with greater flexibility. Unfortunately, I don't think that SE will be implementing it any time soon.
I edit code formatting out of posts when I see it (unless it's used for actual computer code or ASCII drawings or tables), often leaving a comment to this effect:
Please don't use code formatting for highlighting, quotations or emphasis, as it is difficult to read and ugly. Use blockquote, bold or italics instead.
I do this for the following reasons:
- I personally have difficulty reading it; the monospaced font is quite jarring and distracting to me.
- These two ELL meta posts discourage it: one two
- The long standing sentiment on MSE is that code formatting should be only for code or drawing things in ASCII.
Also, in a long post, does anyone find italics hard to pinpoint?
Absolutely. Bold is a much better choice when the emphasized text is buried in a large paragraph.
Since only one formatting tool should be used for each purpose
This is the only part I disagree with. There's no need to limit a particular formatting type to only one word in your post. Go ahead and put bold on everything you want to ask about in the paragraph you're quoting; nothing wrong with that! If you're worried that it will be ambiguous, you can use
<sup>1</sup> in order to demarcate the words or passages of interest. The only other thing I'd say is that if you add formatting or footnote marks to a quotation, please mention what you've added in your post.
Here's the formatting help page; it's worth a peek. In general, these things are for emphasizing, highlighting or quoting text:
These things are not for emphasizing, highlighting or quoting text; rather, they're for what they're named after: