You're confusing your idea of what a photographer does with "photography" as a subject. Photography is an incredibly diverse hobby and profession. Yes, it is possible to only buy one small subset of equipment that lets you photograph a single very specific things well, but I've never met a photographer with such narrow interests.
Even professional photographers that only do a specific kind of photography professional nearly always have amateur interests in other photographic subjects that require different gear.
Far from it, you can also have video games as a hobby and use a 5 year old laptop. A teen that can only afford one camera is not necessarily less into there hobby.
I have even known someone to go the other way and sell off there kit for a point and shoot. They where into candid photos so always having a camera was more important than fiddling with a massive beast.
Granted, camera's are cheap to most of the HN crowd, even blowing 30k over 20 years is just not a big deal. But, just because gear is 'cheap' and 'better' does not make it necessary.
Even professional photographers that only do a specific kind of photography professional nearly always have amateur interests in other photographic subjects that require different gear.