I like your point about signalling. It's also true that the vast majority of people are not fussy about coffee and can drink anything. If you stay on the internet long enough it's easy to feel like you're the weird one for not investing in an expensive grinder or coffee machine or caring about the type of beans you use, while those people are actually the very small majority, they just broadcast it loudly.
What is there to broadcast if you are drinking the same Maxwell House every single day for a decade?
On the other hand, those in coffee culture are always talking about beans to buy, why their coffee tastes messed up this month, how to fix their machines, how to adjust their grind to the latest roast they are trying (every roast needs a different grind).
They're more vocal because there is a lot more to discuss.
