if it is significant, you coded your app wrong, plain and simple

Of course not. It's an explicit feature part of every specification.

Plenty of websites rewrite paths like /a/b/c/d into a backend service call like /?w=a&x=b&y=c&z=d. In that scheme, /a//c/d would rewrite to /?w=a&x=&y=c&z=d, something entirely distinct from /a/c/d working out to /?w=a&x=b&y=c

It's not the application's fault that the people attempting to configure web server URLs don't know how web server URLs work.

Why?