I think it also depends on if you extend "piano" to synthesizers.
At this particular moment, I have a late 1950's piano in the living room -- it was free -- and an el cheapo Yamaha synth in my office. Many folks that I know who primarily sing have a piano rather than a guitar.
While I know that, at one time, people did sing-a-longs and/or used piano rolls for their evening's entertainment, a piano can also be just a fun piece of furniture to have around.
I'm not in my music room, but right now, within 15 feet of me, there are 2 pianos, 2 clarinets, a string bass, a tenor sax, an electric violin and a synthesizer.
That makes 3 keyboard instruments, 3 woodwinds and 2 stringed instruments.
I luv pianos and organs, but I am a terrible player. That doesn't stop me from playing. Upstairs we have Suzy's first piano upstairs with a Thomas organ that my parents got from an estate sale for $15. Downstairs we have a pump organ, parlor grand, and Roland organ with piano voicings. Whether it's a granddaughter plunking on numbered keys, Suzy playing her favorite songs, or me trying a piece before I decide to transfer to a solo, the instruments are in constant use.