[jfields]

As you have said, it is practically impossible to use vectors without mutating their contents with (vector-set! ...), but purely list-based Scheme is actually quite easy to write without resorting to some variant of (set! ...). When practicing on the early problems on Project Euler, vectors and mutation were language features I simply didn't need for some time, so I didn't learn them until later. The building and traversal of lists through recursion got me at least 80% of most problems I solved. Maybe the standard Scheme libraries just do a good job of making mutation operations look like something one needs to avoid whenever possible.