Well, they’re partly correct. If you read scripture, that view has some basis. We are all saints while in a state of grace. We lose our sainthood through sin.
The Church recognizes some people as Saints (note: capital S). These are folks where we have no doubt of their status after death - present with the Lord in heaven. The Church says we have no doubt due to their remarkable or ‘saintly’ life; this is also why the Church currently requires two documented miracles resulting from the person’s intercession.
“Communion of Saints” refers to the fact that we believe the Church on earth and the Church in heaven are one family. Reference the Catechism, # 946 - 962.