Why? The main app requires newer graphics libraries (OpenGL ES 3.0+) and massive RAM (often 200MB+ just to open). On 4.4.2, that app would crash instantly.
This is the safest method.
The last Facebook Lite versions that support Android 4.4.2 are from the (e.g., 350.x). Newer updates may target Android 5.0+. Users on 4.4.2 should install a stable older version or use the mobile web version (m.facebook.com) as a fallback. facebook lite android 442