The examples here make clear that "a clear reason for collecting everything" means an ironclad justification for each field, each bit of precision, each minute of retention. That is not a casual thing. As in, one of the fines here is for retaining a phone number to fulfill a need to communicate, when postal mail could have worked instead.
It is doable, if you have the lawyers and the time. But that's not a degree of scrutiny you want to gamble your life savings on for a personal project.
