questionable advice about Geiser load path setting

[Csepp]

The docs contain this recommended Emacs setting:

@lisp
;; @r{Assuming the Guix checkout is in ~/src/guix.}
(with-eval-after-load 'geiser-guile
  (add-to-list 'geiser-guile-load-path "~/src/guix"))
@end lisp

I haven't been using it for a while because I remember it causing
trouble whenever I was working on other Guile projects.  I have been
running Emacs inside ./pre-inst-env instead, which seems to work just as
well, if not better.

I'd like to make an amendment to the relevant docs, but would welcome
some info on why it was originally written this way, maybe there are use
cases I'm missing.