Hard and soft power. You really don’t get it.

Hard power is the ability to impose one's will by force; soft power is the ability to impose one's will by persuasion or subtlety. In no case does it mean "Utterly failing to push an objective forward". That is a lack of soft power.

Rome split. The pieces continued to act like Rome behaviorally.

In what sense? Your entire bizarre view of Rome is based around an idea that their assimilative institutions were somehow more rigid and formalized than previous ones. European polities after the fall of the Western Empire not only lacked any rigid assimilative institutions, they often rejected assimilation altogether, and numerous ethnicities were born of the lack of institutions capable of assimilating or even maintaining cultural hegemonies in the post-Roman polities.

The remaining institution of Rome, the Roman Catholic church, had incredible power over many of these pieces,

No.

then later soft influence,

The hard power of the Papal States was minimal and regional at best, quarreling with other Italian states and sometimes the borders of the HRE; the only Europe-wide power the Catholic Church had was always soft power.

, over most of Europe known as the holy Roman empire.

...

The HRE was not most of Europe, even at its height as the Carolingian Empire.

The soft power of the church faded with the rise of capitalism.

The soft power of the Church died in the Thirty Years' War, as increasingly centralized states began to deal with issues of pluralism and national unity; itself derived from the Protestant Reformation. The soft power of the Church was dead in the most backwards states of Europe even before the bourgeoisie became ascendant.

We still act like Rome. The behaviors never ended. That’s the through line

Your core objection to the unique influence of Rome was that it 'conquered'; you defined conquest by assimilative processes, but your points have absolutely nothing to do with cultural assimilation or, for that matter, reality.