What they call a timetable is not a timetable. It is origin-destination throughout the day, requiring a tap to Details drop-down to get intermedate stops for each train individually, a sloppy mess and not printable on one piece of paper. It does not contain the information that pdf's once had. It does not show connections.
The times on a pdf can be mainained up to date because every commuter railroad manages to do it. LIRR changes their schedules every 2 months, with far more editions for weekday or weekend engineering-driven changes, and are far more complicated than anything Amtrak has. This is what one of them looks like:
https://new.mta.info/document/85026
This is about Amtrak being cheap and lazy.