You make a mistake many people make when discussing issues like these: the jobs of designers and devs are seperate.
The creation of content by designers and artists like KiddForce, Poshun, etc. generally do not interfere with the development of system stabilization and anti-cheat.
Exceptions exist, of course - for instance, the creation of 64x64 sheet support for the Dark Nexus’ decorative objects likely took a little bit of dev work, as did the overlay present in the O3 fight (and all other uses of it later on).