Author here. Thanks for setting the context: Datawrapper – the data vis tool I write articles like this for – is indeed for people who want to make a point with their charts and maps, often to a broad audience. I agree that people who have learned to read dual axis charts can benefit greatly from them (the same is true for rainbow color maps).

Financial Times journalist John Burn Murdoch changed my mind on dual axes charts – even for casual readers! – a bit over the last six years, too. Here's a dual axis chart he created for the FT: https://x.com/AlexSelbyB/status/1529039107732774913

The next article I write on dual axis charts will probably be a "What to consider when you do use them" one.