Besides, they just 'dev' other projects code - you know, "why reinvent the wheel?"
I have a suggestion for you. Rip out all the code in Dash that came from a another coin. See what's left.
Just X11, Darksend, InstantX... just the two tier masternode code...mehhh
What functions would that be able to perform?
If you rip out Monero code that came from other coins... see what's left...
At this point, a huge amount would be left including the main blockchain consensus code because it has been refactored and rewritten. The PoW has been rewritten and optimized several times. Along with large portions of the p2p (refactored for QoS), various aspects of the RPC (enhanced, in the process of being rewritten). Portions of the wallet (redesigned storage format, deterministic seeds, etc.). Probably a bunch of other things I'm forgetting. So in all a huge amount of code would be left.
That said, it still wouldn't function with the code form other coins removed either. It is fair to say that adopting and adapting code from other coins is very much normal, useful, and appropriate. It is only your friend coins101 who makes an ass of himself by trolling about it.