You are giving a little bit too much weight on Florida in your analysis and perhaps confusing the casuality a little bit. It's not just directly that the Floridians have that much influence, it's that knowing the outcome in Florida tells one quite a bit about, the direction/magnitude of polling errors across the nation.
The 538 model factors in the outcome of Flordida's election with its own belief about the other states results. This is why if you select Biden wins Texas, the model believes the national result likely in landslide territory, the Biden expected electoral college outcome goes up +70, even though Texas only has 38 electors. If Biden wins Texas, he also probably wins in Georgia or maybe even Arizona.
The 538 model factors in the outcome of Flordida's election with its own belief about the other states results. This is why if you select Biden wins Texas, the model believes the national result likely in landslide territory, the Biden expected electoral college outcome goes up +70, even though Texas only has 38 electors. If Biden wins Texas, he also probably wins in Georgia or maybe even Arizona.