It says a "period travelcard" is a zonal ticket valid for unlimited
travel
on LU, Tram, DLR, NR within the zones on the ticket and on all buses.
There are a few short-haul point-to-point seasons still available on
LUL which do not have multi-modal validlity.

The zonal system is simple to follow but not necessarily fair for the vast
majority of travellers who follow one route to work and the same one home.
Probably like most I do use the travelcard aspect on occasions but I'd
probably be financially better off if I could buy a ticket between two named
stations and do the rest on PAYG. The zonal gives you some protection
against problems on one line, but in that case adjacent lines accept tickets
anyhow.

Are there many point to point seasons available still on LU?

Cheers,
Dave