No one is talking about the legitimacy of VII or its binding nature, but about whether or not it meets the criteria of previous ecumenical councils specifically as it relates to defining dogma.
If Vatican II taught heretical doctrines, then it cannot be a Council of the Church.
Councils of the Church that promote heresy are a novel concept of 20th century "traditionalism."
Vatican II did not define new dogma
The very Popes who convened the council have confirmed this point.
"New dogma" is a misnomer. Dogmas are supposed to be logical propositions that exist in the deposit of faith delivered to the Apostles two thousand years ago.
Vatican II was lawfully convened and lawfully ratified by the pope. It defined doctrine, contrary to your claim, which is enough to be considered infallible. Paul VI,
Ecclesiam Suam,1964: "It is precisely because the Second Vatican Council
has the task of dealing once more with the doctrine de Ecclesia (of the Church) and of defining it, that it has been called the continuation and complement of the First Vatican Council."
Furthermore, Paul VI taught that Vatican II contained authoritative teaching, condemned errors, and passed down the Church’s doctrine. In the
Last General Meeting of Vatican II, Dec. 7, 1965, he stated that the council "has made thoroughly known its
authoritative teaching on a number of questions which today weigh upon man’s conscience and activity...
Errors were condemned, indeed, because charity demanded this no less than did truth...This council hands over to posterity not only the image of the Church but also t
he patrimony of her doctrine and of her commandments, the ‘deposit’ received from Christ and meditated upon through centuries, lived and expressed now and clarified in so many of its parts, settled and arranged in its integrity."
Some groups in full communion with Rome reject VII and Rome has not censured them.
List them, please.
If you're thinking about the late
Ecclesia Dei groups and things like the
Institut du Bon Pasteur, they all accept the validity and legitimacy of Vatican II and the magisterium of all subsequent popes.