I suppose it's simply reasonable to say "verify your own holdings". For myself, out of $8,000 in dividends, $20 are unqualified. This is particularly true if you have most of your money in money markets or ETF/Mutual Funds because part of the qualification for Qualified Dividends is the holding duration of the individual security. If a Mutual Fund or ETF is rebalancing or restructuring this is going to trigger capital gains and make some of the dividends unqualified. Similarly, some money markets pay their dividend as interest while others pay it as a true dividend. So that all said, individual performance may vary...but it's definitely an oversimplification to say that "dividends are taxed as ordinary income whereas capital gains are not" since there are certainly circumstances where dividends receive favorable tax treatment, just as there are circumstances where capital gains do not (e.g all short term capital gains are taxed as regular income).
Totally reasonable point that if an individual relies on government programs and needs to remain within certain income limits, that adds a layer of complexity. I would though add that there's no reason that your mutual fund can't realize capital gains over the course of the year, both long or short term, and so if anyone is very close to the line on income cliffs, they should be paying close attention regardless of the income stream and investment portfolio.