As far as I understand one of the main features of Telescope are “Visualizations” that essentially are models that you set up and then they spit out a view on demand. Now builders in Roassal were designed to be the same. Here is the first page of agile visualization book, that is about builders and was first written as an IWST paper that was not accepted:
http://www.slideshare.net/GuillaumeLarcheveque/telescope-introduction-and-example. It tells that there is a #renderIn: method that should be overwritten by a builder developer and which accepts and view and does what the builder should do.
Now some time after this documentation was written, people started develop “stateless” builders that don’t collect all data but instead instantly draw something. I started to complain about this already at that time… Now as I see a situation now is that Telescope is a part of Roassal that Roassal voluntarily refused to be. From my point of view the only reason to do this stateless builders is because they are easier to implement, you don’t have to create single building method and so on. Otherwise they are much harder to use because you have to remember order.