It's the unfortunate scope creep of labels.
Say you are "Baptist," and that tells us almost nothing about what you actually believe or confess (aside from a general idea of your view on baptism).
Say you are "Lutheran," and most people will simply assume ELCA. Even clarifying that you are a "confessional Lutheran" often isn't enough. There's real diversity even among the confessional bodies (LCMS, WELS, ELS, AFLC, NALC, LCMC) on polity, communion practice, and emphasis.
But the label confusion is a symptom, not the disease. What makes someone Lutheran in any meaningful sense is subscription to the Book of Concord, and the real dividing line is not even whether a body claims those confessions, but how it holds them.
Some subscribe quia: I confess this because it faithfully teaches what Scripture teaches. The confession binds. Others subscribe quatenus: insofar as it agrees with Scripture, which quietly makes each person the judge of where that agreement ends. Once that move is made, the confession norms nothing, and in practice Scripture itself becomes negotiable.
That is the actual fault line. Women's ordination, the sexuality debates, and the rest are downstream of it. They are what it looks like when a body treats its confession as a museum piece rather than a binding rule of faith.
So the division isn't really "some keep the Word, some don't." It's that we no longer share an agreed authority for settling what the Word says. Recover a binding confession and most of the surface disagreements resolve on their own. Leave it optional, and no label, Lutheran or otherwise, will hold its meaning for long.