Lots of photographers are photo gear enthusiasts, aka gear-heads. They tend to be affluent people with a technical background who spend lots of time and money investigating, acquiring, testing, and using photo gear. I am not sure whether they use the gear because they collect it or collect it because they use it, but for them the gear itself is a huge part of doing photography. They spend days testing and scrutinizing various aspects of camera and lens function. They banter online about things like dynamic range, megapixels, and read noise. Quite a few are “fan boys”, extolling the virtues of their favorite brand, dissing others, and failing to understand why anyone would willfully purchase some other brand. Camera specifications have fads, just like fashions and hair styles. Once it was the frame rate of power film winders, then it was megapixels, and now it is dynamic range. Reading this stuff makes me wonder how anyone took pictures, much less a good ones, before this year's latest whiz bang camera was available. Spurred on by marketing campaigns, many seem to feel that their cameras become inadequate when a new model with more features and better specifications appears. They even complain that cameras are not updated frequently enough, so they can’t spend thousands of dollars every couple years on something newer and better. There is a name for the phenomena. It is called Gear Acquisition Syndrome, or GAS. Really. Many who have GAS are also afflicted with CMS, or Chronic Measurbatory Syndrome.
It takes a long time to completely acclimate to a new camera. That’s why it is best to change cameras months before using the new one for anything important. Over the years camera transitions can add up to a lot of wasted time, money, and missed or badly captured photographs. Once everything is optimized and using the new equipment becomes second nature, the resulting photographs are nearly always better in some small way under a limited set of circumstances. A gear-head might be able to see the difference in a detailed side by side comparison of large prints, but other viewers in real situations never notice. That is not because the other viewers lack technical knowledge. It is because they look at the content of a photograph and judge it by the emotional impact it has on them. They are not pixel peeping with the purpose of finding barely visible flaws. Gear-heads often don't see the photograph for the pixels.
Once basic picture taking skills are mastered most problems with photographs are more about art than science. Without artistic merit, technical perfection means nothing. With artistic merit, technical flaws matter only when they are bad enough to call attention to themselves. That means it is possible to produce great photographs on a regular basis with very modest equipment. It is equally possible to produce crappy photographs on a regular basis with the world's best equipment. When used properly nearly any camera system is capable of producing files of adequate quality for most purposes. To significantly improve results one must upgrade to a photographer with better artistic skills.
For online posting of “actual pixels” image crops with shadows pushed up by 10 stops to impress forum gear-heads, only the very best cameras and lenses will do. For most other uses any camera with independently adjustable shutter speed, aperture, and ISO settings will work fine. A 35mm film scan or a file from a 2004 vintage 6 MP DSLR can produce a remarkable 18x12 inch print that gives no obvious clue as to its origin. It can hang on a wall beside prints from today's best cameras without anyone thinking it is inferior. Similarly, a 21 MP file camera from a 2007 vintage DSLR can make a wonderful 30x20 inch print. Image quality has been more than adequate to make great prints in this size range for a long time. Things have improved but it takes considerably larger prints to make the advances obvious, and not many photographers frequently make such large prints. A common exception happens in bird photography when making prints of reasonably large size from images that are significantly cropped.
Most serious photographers, especially those with technical backgrounds, have occasionally gotten caught up in the gear-headedness I have described here. Understanding things like tradeoffs between quantum efficiency and charge leakage in CMOS sensors can make us better photographers just like knowing about hydrogen bonds in the molecular solids coloring paints helped Rembrandt. Oh, wait... Seriously though, traits that make a picture compelling have not changed since long before Rembrandt. The easiest and cheapest way to make the biggest visible improvements to your pictures is to spend more time learning art and less time looking for equipment flaws that most viewers will never see. Learn about things like composition, use of negative space, and basic color theory. Go look at a few Rembrandt paintings. It is far cheaper than constantly buying the latest equipment, the knowledge lasts longer, and best of all it has a much more visible impact on one’s photographs.
P.S.: My intent is not to dismiss image quality improvements as completely useless, but they are commonly attributed far too much importance and artistic qualities are attributed too little importance. On the other hand having image quality beyond what one needs or uses hurts nothing. There are people who commonly make prints larger than 30x20 inches, and even when using the longest focal length prime lenses, bird photographers appreciate the ability to crop dramatically while maintaining the ability to make reasonably large prints. Basically, the extremely high IQ available today helps some and hurts none. The most useful technological improvements are probably those that make cameras smaller, lighter, cheaper, and easier to use while maintaining the "good enough for a nice 30x20 inch print" quality that has existed for a long time.
P.P.S.: At some point I may regret writing this. Friend Jay will certainly remind me of it if I ever again rant about a piece of equipment.