In Greater Manchester, the PTE (now TfGM) print their own timetables, but as far as I was aware they charge the operators for them, and have done for years, so in some cases the operator prints their own. So I can't see why SYPTE doesn't continue to print them but charge the operator for them. The expense of producing and printing them is compounded by service changes being far more frequent since 1986. Timetables are almost universally single route ones, whereas in the Netherlands, for example, books containing all services in an area are more the norm, or at least they were before the internet. It is easier to produce one book per year if you align the change dates with the railway.
In Britain, even if you have the printed timetable, you need to be sure that it is up-to-date, and because bus timetables don't have an end date, that's quite tricky. If it is important to have correct information, then you need to use the internet or phone or ask at the information office, and if you are doing that, you don't need the printed timetable.