That is a good question. They sell those CPUs to industrial clients. Note cases can be configured to be completely sealed for high-dust environments, and it is also possible to get industrial motherboards with connections that no regular user needs. The fanless market has a pretty good niche in factory deployments. There, lots of software is designed to run 24/7 on cheap CPUs.
Mac Minis, and in general most Apple products, tend to offer great value in the lowest configuration. But upgrades are expensive. It is a bit of the opposite situation. I have not used Macs for very long, and I prefer Linux, yet the cheapest Mini looks quite appealing. When Intel Core 2 CPUs entered the laptop market, it was a similar situation. The cheapest MacBooks offered really great value compared to competition.
I still find it weird/confusing why would a reasonably high-end brand be selling configs with such horrible CPUs (especially perf/watt considering the whole fanless thing).
But I suppose they hardly have any options if they want a socketed MB. Laptop chips would probably be a lot better value (both cost and heat wise) but then it's no longer modular and e.g. Lunar Lake doesn't(?) even support non soldered-memory...