Are weak Hadith totally wrong?

A weakly authenticated Hadith becomes “Hasan Lighairhi” because of multiple chains of narration

Not one person from among the Imams of the criticism of Hadith has declared such Hadith to be false or fabricated.  On the other hand, these Imams have clarified that when there are other Hadith supporting a Weak Hadith, then this Hadith does not remain Weak anymore, but becomes Hasan Lighairihi, which is worthy of being acted upon.

Hadhrat Mulla ‘Ali Qari (May Allah shower His mercy on him) says:

Translation:  Multiple chains of narration make a weakly authenticated Hadith Hasan (Fairly-authenticated).  (Mirqaatul Mafateeh, Kitab Us Salaat, Babu Ma La Yajoozu Minal ‘Amali Fis Salaat, Vol. 2, Pg. No. 42)

‘Allama Zainuddin Muhammad Abdur Raoof Munawi (May Allah shower His mercy on him) writes:

Translation: If all these Hadith are considered to be weak then because of the multiplicity of the chains of narration, a weakly authenticated Hadith becomes strong and reliable.  Only a person who is unaware of the science of Hadith or is prejudiced can deny this.  (Faiz Ul Qadeer Sharh Jame’ Sagheer)

Hadhrat Shah ‘Abdul Haq Muhaddith Dehlvi (May Allah shower His mercy on him) writes:

Translation: If there are multiple chains of narration of a Weak Hadith, which compensate for its unreliability, then that Hadith will be known as Hasan Lighairihi.  (Muqaddima Fi Usool Il Hadith Lish Shaykh ‘Abdul Haq Dehlvi)