Not a single scholar ever said that the words of the Prophet are as authentic as the Quran except the very few that reached us in the same method of narration as that of the Quran.
The rest of his words (peace be upon him) has always been subject to a scientific process of acceptance or rejection. For that purpose, a lot of sciences was invented, terminology was established, and tremendous amount of work was published.
The scholars have always been using these sciences to research the authenticity of the words of the Prophet; had they not done so, the Prophet’s words would have been lost in the huge amount of fabricated and weak ones. Until this moment, this very critical process are being used for the same purpose.
I tried to learn about these sciences and spent some time reading about them. I was humbled by the oceans of knowledge and the tireless effort spent on this, humility that disallowed me to engage in it without the proper knowledge, tools, and skills.