The reason many people insist that Bitcoin should have a single implementation is that Core has been captured (clear to anyone who witnessed the block size wars), and multiple competing node implementations would challenge their current total control over the network. As it stands the only time the network has seen a change of primary developers was when the current core cabal essentially performed a hostile takeover of the core repo, kicking out the original developers through the use of incredibly impressive social engineering and PR. Unfortunately the tactic was successful and now many apparently free-thinking humans believe that only core can lead the project and the possibility of the free market choosing which software to use is blasphemy.