Maybe you need to stop and rethink what ReactOS is all about (hint: it was never about being an alternative for recent Windows versions). Besides, you need to be able to walk before you can run—and that's what they're focusing on right now, so targeting XP/2003 era APIs is a very practical goal. Also, most of the underlying APIs from that era are unchanged and still in use today in Win10/11, so it's not like they're wasting time here.
Also, ReactOS is not a "plaything", it has actual real-world use cases such as in embedded and industrial applications, where you're running expensive/specialised hardware and you don't have the option to upgrade to a recent supported OS. At my previous workplace for instance, we had a bunch of very, very expensive scientific instruments that ran Windows XP Embedded, each of which had a custom PCI card (not PCIe, mind you) to interface with the core instruments. We had a requirement to securely sync that data to the production network, but naturally you can't connect such an old OS to a modern network. Security issues aside, the protocols used in that era (like SMBv1) were super flaky (we used an intermediary server to sync the data, but the system was pretty unreliable overall). So as an experiment, we installed ReactOS on one of the machines (which was my idea btw), and surprisingly, it all just worked - even the instrument control drivers and software ran without a hitch. This allowed us to switch to the NFS protocol, which made the sync process so much more reliable that all our previous issues was now a thing of the past. I moved on from that role shortly afterwards so I'm not sure if they ever upgraded the rest of the machines in prod, but the point is that it showed that ReactOS was a legit alternative for people running ancient hardware.