There's definitely a lot of benefit to ensuring that students are able to set up their own environment, but also a non-zero risk that front-loading this would put them off / distract them. Also, for short courses particularly, there's a danger that a significant proportion of time (especially for the instructor) is spent futzing around trying to fix broken environments.

In my mind, something like repl.it would be ideal for getting through enough material such that the course participants were motivated and knowledgable enough to setup their own environments at a later stage in the course.