I also vote for putting this feature back into Moodle. I have used Moodle in the past, but stopped using it for several years (because I was working on other projects). I went back to Moodle today to begin a new site install. I installed Moodle 3.3, and added my courses. But I only added the course names and the descriptions -- a course catalogue. Each course defaulted to 5 topics. I stumbled onto this topic, and now realize that I am going to have to uninstall Moodle 3.3 and install Moodle 3.2, because I am never going to know at the course creation how many topics / weeks are going to be in a course, and these values can be anywhere from 12 topics to courses that can have 180 days or even more. The old way of putting in a number in the course settings for the number of topics / sections / weeks was definitely better.
As for the argument about "hanging activities" that can get lost when the number of topics is reduced, there is a simple solution. For every course, create topics+1. The +1 topic is always the "teacher's notes" topics and is never visible to the students and can never be deleted. If a teacher wants 5 topics, in the source code, 6 topics will actually be created -- the 5 topics for the course and the 1 topic that is the teacher's notes section. Any time, the number of topics is reduced and there is an issue with not knowing where to put an activity, because it was in one of the topics that were deleted, those activities are placed into the "teacher's notes" section. This is how WordPress handles side items when a person deletes a whole section from the sidebar and there are modules in that section with settings. Those modules are not deleted. They are just put into an administrator work area.
You can also add an option to "delete empty topics" or "delete topics that are checked". Not all teacher's create topics in order. It is very realistic to enter in the mid-term and final project, and then fill in the other topics.
Also, I think restricting the number of topics / sections is a bad idea, because you don't how exactly a teacher is going to set up a course. But do allow the feature to indicate how many topics to display on a page. This would be similar to a store restricting how many products are displayed on a page. Right now it is only all topics or 1 topic.
Here is scenario that is not a standard course scenario that I am currently working with. I am creating an intensive language course. The course is going to be 5 hours a day, 5 days a week, for 10 months. That is a total of 1000 hours of coursework during a physical school year. Later on I am going to have to break up this course into versions that are two hours each day; and 1 hour each day. Right now, I am not sure if I want to set up the course with each topic being a day (4 physical hours of class time) or each topic being a physical hour of class time. I am going to have to play around with the system to see how things can work out visually and practically.
Bottom line is that the number of topics should be unlimited, but the number to display on a given page should be restricted. If a student knows that each topic is a physical hour of class time and the course is 1000 hours long, they are not going to be "shocked", because they know that is what they are signing up for before they sign up for the course. Or in the case of a elementary school teacher, that is just a standard school year.