Mevans has only himself, Gruk, Karseius, and a few others to help develop the mod.(Sorry if I missed anyone.) Mevans is skeptical of other people aiding him which is COMPLETLY okay. Updates also come out relatively fast, much faster than Vanilla.
Also, with Renewed, its just to risky to take a chance with anyone new. But getting more help would definitely speed along development. Will Mevans ever get more help?