It all depends in context. Paraphrasing may get you off the hook when it comes to plagiarism most of the time, but it's not always the case. For instance, if a given idea is widely popular, paraphrasing might be enough. But it won't hurt to cite the original or significant source.

There are ideas, data, and/or facts that are quite uncommon or even rare, so one should cite the source on top of paraphrasing when writing such content based on them. An excellent example of this is research results.

The basic is rule is, if you got an idea or a concept from someone or somewhere, you should mention them as your source.