Why are there no seatbelts on a train?

Have you ever wonder why there are no seatbelts on a train?

I found two reasons online:

One reason is the gradual deceleration of train because of its massive momentum (source):

For the same reason as heavy trucks don’t. A seatbelt is of most use where a collision causes rapid deceleration.
Trains carry so much momentum that they do not stop rapidly, even in very severe collisions.

Guardian

Second reason is a choice to use ie. crashworthy seats instead of seatbelts (source):

Trials with dummies took place with face-to-back ‘crashworthy’ seating currently used on trains, which is designed to deform when struck by the knees or head of the passenger seated behind it.

In simple terms, the observation in the case of two-point lap belts was that the rear passenger’s body rotated around the hips so that the head struck the back of the seat in front in a way that could break the neck.

When three-point belts were tried out, it was realised that the crashworthy seats were not strong enough to provide anchorage for the diagonal belt. The result was that a choice had to be made: belts or crashworthy seats?

Railway Gazette