I also did solutions without prepending or reversing, if you are interested.

I've done a ruby solution that doesn't use a reverse or prepend.
(I've also done one that does, so make sure you're looking at the right one.)

What you are saying is not correct, or you are precluding things that are not precluded by this kata. I can't say more without spoiling the challenge. The test do not preclude you from using reverse, although the description says you should try and avoid it. So I suggest you submit a solution and then look at the solutions submitted and see if you cannot find one that does not use a reverse operation.