Historically, older versions like 6.6.0 are favored for their compatibility with legacy hardware and simpler Android versions (like Android 6.0 and 7.0). Many users find that newer versions are "bloated" or have UI changes that don't perform as well on older, low-end devices.
If you prefer the old-school, straightforward interface before things got cluttered, this is the version for you. lucky patcher 660 better