DHCP vs ICMP Message Type 9 and 10

Dear Gents,

I was reading the ICMP messages and found with the help of ICMP Type 9 and 10 host could automatically discover the identity of local routers, and learn important information about them defined in   RFC 1256.

Also in one of the book it was written that this is Router Discovery Message is an alternative option of DHCP.

When we have built-in facility of ICMP what is the need of DHCP Protocol.

Appreciate to comment the differences.

Thanks

Jawwad