That's overstating the "case" (pun!). Ignoring or normalizing case is different from ignoring a non-redundant URL with uppercase. But it might cause problems

That's overstating the "case" (pun!). Ignoring or normalizing case is different from ignoring a non-redundant URL with uppercase. But it might cause problems if the IIS server isn't properly case-preserving to normalize back to the standard (possibly capitalized) form. Mac filesystem was nicely case-preserving but case-agnostic in this way, going back decades.