Not really - the system partition is ROM, and they can be disabled. They just survive a factory reset, and putting apps that are supposed to survive factory res

Not really - the system partition is ROM, and they can be disabled. They just survive a factory reset, and putting apps that are supposed to survive factory reset in the system partition is what the Android developer documentation explicitly states you should do. But if they're disabled they do not run, and can't run, so the implications for performance and security are zero. The only conceivable impact is that some storage is used up, but as seen in the other comments we are talking dozens of megabytes here, and the article is completely wrong about the partition size.