Because this forum is the center of the Pokemon ROM Hacking community, at least for English speakers. While PC could also be claimed as the home of Pokemon Essentials, the ROM Hacking community existed long before Essentials, and it's taken years to build up this much of a community at all. At one point this forum was buried deep and it got very little exposure to PC's member base at large - and that remains a problem to this day. Plus, proper game development requires a much greater investment, and a lot of those who find themselves involved in PC's ROM Hacking community are kids looking for a hobby that they don't have to spend much time on.
So, if anything, I blame the school system.