i think rg article are not a good source, because everyone can upload a file even if it not peer reviewed. you can use scholar article or databses such as sciencedirect, and if you need free downloaded articles use sci-hub.tw
To elaborate some on the question and answers it is important to do several things:
1 - If the article or chapter is published by a reputable publishers/academic society it is probably worth considering.
2 - Make sure the journal or publisher is NOT a predatory source. Even with this, some reputable journals have published very poor quality articles, so be careful about every one.
2 - Some members of RG put a paper they are working on into their "Research Items" list when they should put it into the "Projects"k category, and thus these should not be cited unless there is some very important reason to contact the researcher and list it as 'personal information' in the paper (can be in citations in some journals, others in text).
Every author can benefit from researchgate by choosing the best research from different authors also try to check the journals that they publish in it before getting these articles as a reference
ResearchGate does not publish articles, rather published articles in journals are uploaded by researchers to their accounts. Certainly you will get large number of good uploaded articles on the site, which you can use as references for your research work.
It depends on the article context and the journal so whether in RG or other site you will seek the same infos to decide if the paper is a good reference or no...