Several reasons. Etiquette. Less reason mangle the words of others (arbitrarily cutting something out of larger context can also easily mangle). Let's your reader see how you understood the communication, not just that you found it somewhere and copy-pasted it in.
Disagree; adding context or identifying of an unusual pattern as part of the quote is common practice
> Less reason...
> Let’s [sic] your reader see...
These two points are at odds with each other - and how would my reader understand the contrast between the source and my interpretation without knowing the source?
A larger quote would still be arbitrarily cut out of a larger context. If you're extending past the good part purely to get a subject I'd even say it ends up more arbitrary.
Unless you're taking a test, you don't need to prove you understood it, and if your reader lacks confidence in your understanding then paraphrasing makes the problem worse! Instead of merely worrying you missed important context, now they have to worry you completely altered the meaning.
Paraphrasing can mangle words so easily. I'm baffled why you would imply otherwise.
It’s a convenience to the reader. If I paraphrase a reference to support my point, it’s more work for you to determine if I’ve done so correctly. If I quote and update a dangling reference, it’s much easier for the reader to decide if I’ve done so in good faith and without introducing significant bias (whether intentionally or inadvertently).
I think it’s more faithful to the original, at a slight cost of fluid readability, which is often a good trade-off of features.
You seem to be misunderstanding. Square brackets are not paraphrasing, they are correcting words for context. They should not alter the meaning, as paraphrasing often does.
