Are weak Hadith totally wrong?

<i><b>&nbsp;A weakly authenticated Hadith is acceptable in issues of excellence:-</b></i> <div>&nbsp;</div> <div>All the Hadith experts are in consensus that in matters of excellence (Fadhaail), a weakly authenticated Hadith is to be acted upon. &nbsp;Thus, Imam Abu Zakariyya Mohiuddin Yahya Bin Sharaf Nawawi (May Allah shower His mercy on him) has clarified this at various places in his writings:</div> <div>&nbsp;</div> <div>Translation: The scholars of the Ummah all hold that it is permissible to act upon a weakly authenticated Hadith in matters of excellence. &nbsp;(Sharh Al Arba&lsquo;een An Nawawiyya, Muqaddima, Al Majmu&rsquo; Sharh Ul Muhadhhab)</div> <div>&nbsp;</div> <div>The Ummah&rsquo;s acceptance of a Hadith is a sign of the Hadith&rsquo;s authenticity</div> <div>&nbsp;</div> <div>The Imams of Hadith have written that because of Talaqqi Bil Qubool, a Hadith is strengthened. &nbsp;&lsquo;Allama Abu Abdullah Muhammad bin Jamaluddin (May Allah shower His mercy on him) has written:</div> <div>&nbsp;</div> <div>Translation: A Hadith which the Ummah has accepted is sure to be rigorously authenticated (Sahih). &nbsp;(An Nikatu &lsquo;Ala Muqaddima Ibn Salah Tambeeh)</div> <div>&nbsp;</div> <div>&lsquo;Allama Ibn Salah has written at another place:</div> <div>&nbsp;</div> <div>Translation: &nbsp;When a weakly authenticated Hadith is accepted by the Ummah, then it will be acted upon as is the authoritative opinion.</div> <div>&nbsp;</div> <div>Imam Suyuti (May Allah shower His mercy on him) has written in Tadreeb Ur Rawi:</div> <div>&nbsp;</div> <div>Translation: &nbsp;When people accept a Hadith, then it will be judged to be rigorously authenticated (Sahih) even though its chain of narration may not be rigorously authenticated. &nbsp;(Tadreeb ur Rawi Lis Suyuti Al Awwal Us Sahih)</div> <div>&nbsp;</div> <div>Thus, if a Hadith reaches the status of Talaqqi Bil Qubool, talking about its reliability or unreliability and investigation about its narrators is entirely unnecessary. &nbsp;For this reason, the unreliability of some narrators will not affect the deductions drawn from this Hadith.</div> <div>&nbsp;</div> <div>Imam Shamsuddin Sakhawi (May Allah shower His mercy on him) has written:</div> <div>&nbsp;</div> <div>Translation: When the Ummah accepts a Weak Hadith, then as per the authoritative opinion, it will be acted upon, so much that it is of the status of a Mutawatir (frequently occurring) Hadith, which can abrogate the Nas Qata&lsquo;ee (the canonical proofs) &nbsp;(Fathul Mugheeth Sharhu Alfiyatil Hadith Fi Ma&rsquo;arifati Man Tuqbalu Riwayatuhoo Wa Man Turaddu)</div>