Because very large share of market now are datacenters. Difference from desktop is dramatic - for desktop really acceptable very simple chips with bad energy efficiency, but DCs already deal with extremely high power consumption, as they typically "compress" so much consumption in one rack, that constantly working near to physical constraints.
You can't make desktop computer 4 times larger but there's very little preventing you form putting 4 racks where you had 1 before. If the floor space is the expensive part of data center then probably some incentives are misaligned.
That's the AI hype narrative, but aren't server CPUs only like 25% of the total market? That's tiny compared to consumer volume, though revenue is likely on par given the higher cost per unit.