Not for most of its history it wasn't. Between the New Deal and the early 1990s, though, there was a long shift in party alignment that had both major parties being ideologically incoherent big tents in transition between the past (ideological and more so geographic) party alignment and a new ideological, national alignment. This produced something that looked like more centrist politics, but it wasn't really fundamentally so, and in any case it was a manifestation of a transitory, inherently unstable, state.
> The toxic partisan nature of it, which both sides are currently doubling down on, is largely a modern invention.
No, it's not. See, the 1860s for a fairly vivid counterexample.
I'm not debating 19860s politics, I'm talking about the growth of the modern state, largely post WW2. Which has rarely been partisan.
It's been intensely partisan and intensely sharply ideologically-divided, just as today. What was different during the long realignment from the New Deal through approximately the Contract With America (though definitely progressively weakening during the last couple decades of that period) is that the ideological and partisan divides were not in sync, because of the lack of coherence due to the ongoing partisan realignment.
Because political power players had to manage both conflicts, the tension between their interest in one vs. the other often served to moderate conflict.
The unending increase in size and scope of government has been largely separate from this, and was a feature of both parties despite rhetoric for much of the last century. Not just in the US but in every western country.
Saying that government has been stripped of power by x party simply doesn't hold up to facts. If anything the power has consistently increased, or at most occasionally plateaued or massively increased in other areas. But most importantly only a few well connected individuals and companies are getting exceptions to that rule, in special circumstances.
Which is exactly what this law change is about: it explicitly says it will only be done in special circumstances. Their power to regulate asbestos has not been diminished at all, they've merely further solidified cronyism and legislation-by-special-favour into law.