RPCS3 fully operative

RPCS3 was released about 10 years ago and there are many video games that not working at all or not working properly. I'm wondering why? Is it from the game itself or is the emulator not good enough? 
Like if you see PCSX2 it's working perfectly and also PSX emulator.
 When will RPCS3 be 100% ready?

The PS3 is way more complex to emulate than the PS2. Proof of this is that RPCS3 can use up to 16 cores/threads, maxed out, just when emulating one game.

The PS3 was just as complex for developers to program games for back in the day. The architecture, in a nutshell, was and is a headache, just like the Sega Saturn was. from 2 generations prior.

That said, my PS2 library is bigger than my PS3 and I have multiple games still not working properly in the latest dev release of PCSX2. I am not sure where you got "perfectly" from.

My favourite titles are not working on RPCS3, it seems to be the big games, so I agree that can be frustrating on the patience, but patience is all we have, and overall, they have done a spectacular job.