IIRC, the billboard originated with the PC 952 and 945 models, S&W wanted competitors on the shooting lines to know what they were competing against and to differentiate them from 1911s and other manufacturers. They pre-dated S&W getting into the 1911 game.
Totally true -- but we must also mention that both of these models evolved away from the billboard. The 952 no-dash was a billboard pistol made to (supposedly!) 400 units. The larger share of the 952-1 was a billboard design that looks exactly like the no-dash.
The last group of the 952-1 was a non-billboard design, and then S&W carried that understated look to the new stainless 952-2 pistols.
The 945 began life with a size 24 font "
9 4 5" on the slide but there were
soooo many 945 variations in look, style, lettering, serrations and colors/finishes, along with four distinct sizes. With the 945, they too evolved and the billboarding went away, it's just not nearly as easy to say when and where as it is with the 952's.
It's also worth mentioning for anyone that had never heard of this term that "billboarding" is not a S&W specific aesthetic, but plenty of different gun makers have done it. I think if we speak generally... it will always be looked back upon as somewhat less than attractive.
My biggest billboard
pain is that my one single favorite firearm beyond all others sports a really unattractive billboard script. It's the PC 845 Limited second series, "Model of 1998" and it says that in irrationally large letters taking up most of the left side of the slide.
For me and my journey, this pistol exists in it's own single spot above all others in my heart and YET, I genuinely hate this homely, silly nonsense carved in to my phenomenal stainless pistol.