Quote from: UserU on Today at 01:54:48 PM

For instance, we can see the difference between "I read an article on CoinDesk that (this guy) claimed that Bitcoin will reach 0" versus blatantly copying a quote or source without citing any source.

Clearly. It (also) depends on how much "purist" is the one who "checks" for plagiarism.

Quote from: UserU on Today at 01:54:48 PM

IMO, that doesn't fall under plagiarism because you did specify that the content was sourced elsewhere.

Well, while I would (mostly) agree with you, OP has clearly stated that not citing the source correctly (which is clearly there in my case, since my example even tells "I've read somewhere" instead of "I've read on CoinDesk") falls under "unintentional plagiarism". And that's what I try to point out.
As you see, people already have different opinions on that. My take is that it depends on how is the idea formulated afterwards. If it's (almost) identical text as in the source article, it's probably plagiarism. If only the broad idea is said then it's probably not plagiarism, it's just discussion (the possible culprit receives the benefit of the doubt)