Why not search the directory an ELF binary resides for dynamic libraries on which it depends?

I know that for security sake, "." is not included in $PATH, in case that root run other user's "ls" instead of the /bin/ls, which windows do.

But I don't understand why linux not search the directory an ELF binary resides for dynamic libraries on which it depends. If Linux do, then "--prefix" is not necessary when running configure, and elf binaries can be made portable.

The security problem won't trouble, if Linux searches $LD_LIBRARY_PATH first, then the directory binary resides.