question about multiple CNAMEs?

[Clenna Lumina]

In chapter 17 of DNS & Bind, 5th ed, ph 485, it says, right under the 
heading "Multiple CNAME Records"

Quote:

   One pathological configuration the honestly hadn't occured to
   us [...] is multiple CNAME records attached  to the same
   domain name. Some administrators use use this with round robin
   to rotate between RRset. For example, the records:

        fullmonty IN CNAME fullmonty1
        fullmonty IN CNAME fullmonty2
        fullmonty IN CNAME fullmonty3

   can be used to return all the addresses attached to fullmonty1,
   then all the addresses of fullmonty2, then all the addresses
   of fullmonty3 on a nameserver that didn't recognize this as the
   abomination it is.


What I want to know is, why is this so bad? I can understand resolution 
can take slightly longer (ask for fullmonty, get fullmonty2, ask for 
fullmonty2, get one of fullmonty2's ips), but it seems that coul be a 
very useful feature, as described above - have something like:

  www1 IN A     200.10.100.10
  www1 IN A     200.10.100.20

  www2 IN A     200.20.100.10
  www2 IN A     200.20.100.20
  www2 IN A     200.20.100.30

  www3 IN A     200.30.100.10
  www3 IN A     200.30.100.20

  www  IN CNAME www1
  www  IN CNAME www2
  www  IN CNAME www3


I understand that I should not use such a scheme from reading this book, 
mainly the "CNAME and other data" rule, making CNAME a singleton RR. 
What I don't understand is why CNAME is a singleton and why the option 
to allow multiple CANMES was removed in Bind9? I mean why is CNAME 
regarded so differently than n A record?

When I look at that page in the book, a config liek that seems like it 
could be perfectly valid, and I could envision a large scale corporation 
or so using such a setup to spread load. I can also see how it coudl be 
gross overkill too, but how it's used should not dictate if it _can_ be 
used, should it?

I just want to know why such a setup is considered so taboo, other than 
possibly making initial unachached queries that much longer?

-- 
CL