Short computer names cannot contain dots, but host names and full computer names can. And they can be resolved without any DNS.
It is not "waste of time".
For ex., my workgroup Windows XP "Full computer name: pblack.primary.dns" (short computer name + primary dns suffix on my comp) is resolved, without any DNS server or entries in any HOSTS, both by pblack and by pblack.primary.dns
DNS is external to computer resolution mechanism which may simply absent in certain cases like small workgroup or, even does not make any sense, for ex., in internal (to computer) name resolutions.
Note that short computer name is one per computer but host names can be multiple.
Unfortunately, there is no point to seek the truth because MS docs are mess on it.
Broadcasts are made by ip-address.
"NetBIOS broadcast" is broadcast with preliminary resolution of NetBIOS host name to ip-address. For ex. by communicating with local cache, local DNS cache/resolver, WINS server, lmhosts, DNS Server (which may have WINS forwarding), etc.
I doubt that NetBIOS resolution is used in Windows XP (I've read that it is legacy). I am inclined to believe in CIFS/SMB or SMB direct. What is NetBIOS name when MS insists that NetBIOS is used for compatibility with pre-Windows2000 OSes?
Om my Windows XP I do not have either DNS or NBT (NetBIOS over TCP/IP) or hosts/lmhosts entries which do not hinder it to resolve host name with dots.
I always thought that NetBIOS name is single-label name and broadcast is by ip (not by any symbolic name).