My wife, bless her, is lousy with money. She has never saved a dime in her life. She spends based upon perceived need/utility rather than what funds are available. So for the 32 years we've been married, I've handled the majority of the finances - most the bills, savings, and investments.
There is no question that were we to divorce, there would be no distinction between "her money, my money." But it's also true that our informal division of financial responsibility - you use your money for these things, I'll handle everything else - has very effectively served to limit the financial liabilities she has wrought. "Your money, my money" marital divides are certainly not a panacea (my wife could easily have overspent her bucket, for instance, incurring debt we'd both be responsible for), but they can very often help when couples are not of a like mind on saving/spending philosophy.