RDFa/Microdata is more interesting for people whom sell objects instead of content. e.g. marking up that a page is about a kitchen cabinet that is 60cm wide and in the color white might lead to more sales in the long run. As people whom are looking for 60cm wide cabinets might get to your page instead of one about one 36 inch wide.
That's an oddly specific search and even Google doesn't have any kind of tools for queries like that.
What is more likely is that you'll find companies specialized in selling cabinets and they'll have a browser/search to restrict choice by given dimensions.
There is not a lot of benefits for them to expose all that data to various search engine, best case scenario they end up competing with a bunch of other brands on a generic search engine page where they have absolutely no control how things are presented etc...
And even before thinking about that, you can actually put the dimensions in a description, which some do (like Ikea) and Google is definitely able to pick up on that, no RDFa was ever needed. As far as I can tell, LLMs can work that out just fine as well.
The problem with the metadata discussion is that if they are actually useful, there is no reason that they are not useful to humans as well, so instead of trying to make the human work for the machine it is much better to make the machine understand humans.
It sounds harsh, but maybe that was never a good business model in the first place. And I fully realize that this includes most news sites. In order for the web to grow, I think we need to figure out some way to get past banner ads as the only way to make money. It's been 30 years.
