With that logic we could also get rid of the girldc keycap thread and any other thread and just simplify all threads into "post your keyboard" because post your qfr or post your ducky is still marketing, whether it is done by someone else or the company themselves.
Honestly, I think the GirlDC and Clacks thread should probably just be a post your custom keycaps thread, but they're so established and a part of the community that changing anything is unlikely to happen. They've long been cornerstones in here. Not only that, but they were started by people other than those providing the service. Mkawa, moderator supreme, created those threads.
Unlike the Clack and GirlDC threads, these were created by the people providing the service to explicitly market their specific services (ListKoi) and cases (Gon). Unlike the Ducky example you gave, they do not even make their own PCBs. There's a reason that all the Korean Keyboards are kind of lumped together, they were small production runs or used a PCB from a group buy for a custom case. So you'll have Phantoms, GH60s, and so on in here that all already have their own thread.