To be honest, I don't remember exactly what the situation was in Moodle 3.5.
There was a big push to get all the legacy cron converted to use the new scheduled task system (MDL-61164). Some of that was done for 3.5, but some of it was not finished until 3.7 (See the linked issues.)
There was a big push to get all the legacy cron converted to use the new scheduled task system (MDL-61164). Some of that was done for 3.5, but some of it was not finished until 3.7 (See the linked issues.)