Hello Silverback,
In response to your post, the reasons for hosts (I assume you mean submissive hosts) not greeting guests with offers to serve drinks are varied and shared by both dominants and submissives alike. The act of serving a drink means different things to different people and is in no way meant as any lack of regard for you or anyone else.
For some it is an act of submission to be reserved for one's dominant partner or one with whom they are engaged in a scene.
Some view these serves as a form of flirting or a prelude to a scene, which is understandable as many scenes develop in this way. Because of this view, the unsolicited offers of servitude from a submissive are seen as bold and in violation of protocol.
Others, such as myself, see it as a simple act of courtesy, one I extend to both dominants and submissives alike, from time to time. However, I believe I am always courteous and when I am of a mind (and not engaged in too many private conversations) I occasionally place a refreshment cart against a nearby wall and encourage guests to feel welcome to help themselves at their leisure.
I hope this response helps you feel more welcome, Silverback. I look forward to crossing pathes again.
Warmest regards,
Donna