It was lost due to Tesla's decision to remove MobilEye as a supplier.
Mobileye generally focuses on highly optimized HW/SW that does individual things very well, in a manner similar to how factory automation works (e.g., they basically built a "lane keeping + auto-braking + sign reading" appliance).
Tesla decided that 1) It was bad to outsource automation 2) Starting from scratch and 'learning' how to drive using ML was better than iteratively teaching a car how to do discrete tasks very very well (this is why Autopilot regressed a bunch in 2016).
In general, it's another symptom of Elon's 'I have an extremely specific idea, let's figure out' mentality that sometimes works and sometimes results in useless tunnels under Las Vegas.
LKA is just that, an assist, because if you let it drive it’ll bounce back and forth between the lane markers, not keep you seemingly centered.
Hyundais have exceptionally-good lane-following.
Edit: You can also accelerate without disabling it.
Or maybe I'm just salty that my cruise control has never worked.
Eh? Yes they do. Bizarre lie.