You can test this with your own history. I switched from an Olympus OM1-N camera to a Nikon F70 and then the Nikon F80 until I switched to digital. I then used a Nikon D50 and then Nikon D70, before moving to Nikon D5100 and then the Nikon D5300. Each stop of the way I was tempted to go to the higher end models. After much consideration, I concluded that I would never use a lot of the features of these newer models, and the models I use have all of the core things that I need.
I believe, as do many others, that it is better to focus more on the lens than on the camera itself. We are now seeing the pressure to move to mirrorless cameras as the next step. To some extent, cameras are becoming like mobile telephones in which the main function is just one more function along with all the other things those pieces of equipment provide. Do you need that in order to be a better photographer? I don’t think so. A good photographer can take a good picture with an adequate camera and lens, but the technology itself will not turn a mediocre image into a “wow” image.
If you think about it, when the Olympus OM-1 was the mainstay of the working photographer, world class images were captured and made. While the Nikon D70 could not do many of the things that the top-line Nikon camera can do today, at the time it was far more advanced than a far more expensive camera of 15-20 years earlier.
Here is an example. This image of a canal boat pilot in Amsterdam was made ten years ago, in 2008, with a Nikon D70. The D70’s highest resolution ISO was 200; this was shot at that, and at 1/400 second with F5.6.
As processed, I produced this image.