why would they think that the Catholics in this forum do not accept the Catholic faith in its entirety?
Well the SOP of the area itself is an indication that the fullness of the Catholic Faith as taught by Rome is not accepted: "This area allows for what would normally be considered by Rome dissent from the teachings the Magisterium of the Catholic Church."
That is not normally understood as dissent by a message board, that is normally understood by canon law and Rome.
Liberal Catholicism accepts Liberal Theology...that the deposit of Faith can change to conform to the world. Not in a development of of Dogma sense in an accepted way...but in the sense that Dogma can change because it is based in social norms and not revealed Truth in itself. That is not a concept the Catholic Church will ever allow.
Now one can argue that there are Catholics on the other side of the argument rejecting things that they should not. But yes...there are some unchangeable things that are promoted here and the SOP allows. By the very definition, that is not accepting the Catholic faith in its entirety.
People keep asking what a Liberal Catholic is. A Liberal Catholic has nothing to do at all with politics. A liberal Catholic embraces liberal theology. For a Catholic that means that they believe that the Deposit of Faith is, in part, based on social factors of the time of Christ and after and can change in it essence. Not that we grow in understanding of it but that the Deposit of Faith is changeable in its clean and definite teachings because we now know better.
In that...yes, they reject part of the fullness of Faith in Tradition and Scripture. Do others on a far conservative edge to it to...yep. But that is a different matter.
No matter what TLT is socially or politically, it is (intended to be) a safe haven for the Liberal Catholic beliefs. Beliefs that, By their definition, are at odds with Rome.
So the SOP itself indicates a rejection of the Fullness of Faith as Rome has constantly defined it. Now that is not to say they do not have reasons for believing as they do. But I think it is fairly clear some do reject parts of the Deposit of Faith and the Teachings of the Church considered unalterable.