It's really odd to me that having an advanced ceramics division at Toto is considered such and odd diversified activity, and on top of that making money from the expertise of that division. Deep knowledge of ceramics would seem to me, to be a fundamental advantage if your main line of business is making ceramic toilets.

Companies like this with deep interlocking expertise used to be common in the US too when the US actually made things. GE was a conglomerate of "diversified" expertise - at least until a grandfather of financialization laid the seed to take apart the company.

AT&T and Xerox used to maintain all sorts of deep expertise in all sorts of science and technical activities - though maybe it could be noted that they were famously bad at spinning out other diversified product lines. But the expertise was a need in their core activities. Maybe the most interesting thing about Japanese businesses is that they have shown how to successfully start and maintain diversified product lines.

The main reason we are surprised by these "diversified" products, I suspect is that the typical American (and HN reader), is just not very familiar with the wide range of expertise needed to actually run manufacturing businesses.