I am not buying this argument.
America for better or worse (mostly worse) has a two party system that in practice functions as mostly a uniparty prioritizing defense spending, entitlements, and the economy, with some lip service paid to red meat/blue meat issues to ensure power is maintained. This means you can reliably predict what American policy will be in any given moment for any given president.
Besides, EU member states have had much more iteration on their governments, policies, regulations, and parties. It's not uncommon for a European country to have 7 different parties. And unlike the US, EU's don't hold their constitutions in a such unchanging high regard. Ours is purposefully difficult to change. France, for example, on the other hand, has changed its constitution twenty-five times since circa 1958.
edit: I took out He-Who-Must-Not-Be-Named because it seems even here on the board of Very Smart People ™ we can't help ourselves when we see that name and ignore the rest of the point someone tries to make.