I believe that it is the reason :D
Why? because the development team don't have communication and are not organized from what we are seeing here!
1. They fix a bug, few days/weeks later it get bugged again.
2. They make one fix, the implement it directly on the server (requires reboot/may and will cause temporary lags)
3. Let's say we have a file that contains MoP quest-line script in it, Pandawow gives the development team to fix it, but as you can see:
They fix, they implement. and then another developer takes the same file, he/she fix, he/she implement; and that's the reason why when they fix something it get bugged all over again.
Every developer is working on the original file (not the updated one) and then they implement (overwrite on the new/updated one), it's like if we're stuck in a loop XD
4. They fix something, and without noticing, they bug other thing.
Again, LACK OF CODING SKILLS :)
I hope this is clear to everyone now, and if not, this picture will summarize what I said 100% :D