The argument is also flawed because favourite is not important. If you asked someone what their favourite food was they may say Chinese takeout. If you asked them what their most important food was, they may say Sunday dinner because it reminds them of their deceased mother. There is a significant difference between the two, one is a personal preference but the other could compromise a bigger part of one’s identity.
Here’s a thought experiment:
Which book is more important? The book that the most influential man in the world considers the most important but which nobody else has read? Or the book dismissed by all elites but that is the most important book to the least influential billion people on the planet?
I’m quite aware that you can’t eat Hamlet.
Notice you said Shakespeare is taught in high school. In that sense it carries importance in that people are exposed to it whether they like it or not. But it doesn’t mean that once those people leave school it continues to be of importance to them and to most people I would argue it doesn’t. The majority of people run a mile when you start mentioning Shakespeare because they have less than fond memories of being sat and forced to read something written in archaic English that in the present day requires either a teacher or another book written in modern English to understand if you have never encountered it before.
The original comment talked about “most important novel of the century” which is a ludicrous claim. The assumption in that sentence is that there is a universally agreed upon consensus for evaluating literature in comparison with other literature that allows us to rank them like you would football teams in a table and that the commentator’s choice is the undisputed winner of this gladiatorial death match. If you can point me towards this criteria please do so. Otherwise what you actually have is ‘This is the most important thing to me so I’m going to assert grand unprovable statements as proof in order to propagate my personal tastes and beliefs”.