People do just say H when they are pissed off with him! Or "D"H.
Other than that though, you kind of need the D part - all the alternatives don't work.
Referring by name e.g. Brian, Joe. We have no idea who that is, is it your husband, brother, son or dog?? Also privacy issues. Most people don't want to use real names.
Using a relationship descriptor e.g. my son, my husband, my daughter. Clunky and doesn't flow in a conversation. You need a noun that you can substitute for the name rather than writing "my youngest daughter" 12 times in one post or constantly using he/she and not knowing which person that refers to. DD2 is easier, and everybody knows what it means.
Use a single letter e.g, S, D, H. Except for H which tends to be clear, it's just not used enough so tends to have the same issue as using full name.
DH/DS/etc predates MN and has been internet forum vernacular since the old usenet groups and email chains etc. It might not be perfect, but it works well enough and there's no need to reinvent the wheel.