I agree that 401k rules are not ideal. It seems reasonable that once you have X dollars in it the tax advantage should stop. Why should the government encourage me to save more money when at age 30 I already have hundreds of thousands of dollars in a tax-advantaged retirement account?

However, the article doesn't spell out the political case for how this would happen. The 401k is a vehicle that provides the greatest benefit to the middle and upper middle class, the largest class of voters, so I can't imagine it would ever be cut. Rules like the SALT deduction still have strong support even though they are way more niche/economically regressive than cutting 401ks.