This is surely a tricky topic that I must investigate but I can say for sure that Nishant's quoting of Humani Generis is OUT OF CONTEXT, therefore he must have some agenda, considering he left out the most important part of the paragraph he quoted.
20. Nor must it be thought that what is expounded in Encyclical Letters does not of itself demand consent, since in writing such Letters the Popes do not exercise the supreme power of their Teaching Authority. For these matters are taught with the ordinary teaching authority, of which it is true to say: "He who hears you, hears me";and generally what is expounded and inculcated in Encyclical Letters already for other reasons appertains to Catholic doctrine.
The phrase Nishant left out is extremly pertinent to the topic, because the pope is saying that, supposing the encyclical appertains (ie relates) to doctrine, then one must give consent. Certainly no one would disagree with this.
However, this changes the dynamic of the quote, since doctrine is of a higher infallibility level than the "Ordinary Authentic Magisterium of the Roman Pontiffs", with which Nishant was trying to connect to the quote. BIG DIFFERENCE! Everyone has to give assent to doctrinal matters; we only have to give consent to the ordinary magisterium insofar as it does not contradict previous doctrine and/or conciliar statements.
As an aside, V2 and most of the post V2 enclycicals do NOT deal with doctrine, therefore we do not have to give the same (or in certain cases, any) assent. This agreement is trying to require doctrinal-level assent on non-doctrinal matters.