It's not my favorite analogy. Probably something closer to the government of early modern Poland: so paralyzed by dysfunction that it couldn't effectively govern or respond to novel threats.
I've wondered if public dialog about societal change might be improved by having a richer set of exemplars, to serve as context and landmarks in discussion.
When exploring design objectives with a client, one often provides a set of proposals, whose differences then serve as a vocabulary for discussion. Almost a basis vector set. Public dialog often leaves me with the impression of a client with an inadequate set, an impoverished vocabulary, struggling to both clearly understand and express their opportunities and desires.
For governance and society, even just current US States are variously diverse. So we might discuss whether we want aspect X of the federal government or national society, to look more like those of this state or that state, with a bit from some other. Current countries and societies provide even larger breath, and history even more.
But the goal here isn't models, merely vocabulary. Not "if we do this, then these experiences suggest these results". Such extrapolations between highly complex systems are almost silly. Though experiences can suggest possibilities. But my focus here is more on creating vocabulary. For example, I recall a story of "you don't call the police in <city in Brazil>, because they will just show up in force, smash things and people unrelated to the problem, and then leave, having done nothing but additional harm". For vocabulary, it doesn't matter whether that's true, or typical, or happens only under specific conditions, or is different now, or whatever. It's merely a tag, to facilitate discussion and reflection like "Hmm, it seems there are a few situations of that in the US too! What is the shape of such cases? Does it vary among municipalities? Why? What does the space of shapes look like? What are the class, cultural, political, and professional contexts?", etc.
With that out of the way, what substantive arguments can you make that leads you to think this is anything like the fall of Rome?