First, as an aside, Canon do not make a D5, Nikon do. Canon makes the 5D series. 🙂
To your point, I think it is fair to say that outside professional sports photography, where connectivity is a critical component, and improvements tend to result in upgrades as soon as those are available to upload images in as close as real time as possible to agencies, papers, magazines and web publications. Getting an image of a sporting event like the Olympics out to the public is an incredibly competitive and demanding business.
For a lot of non-sport applications, considering the cost of updating gear, professionals take the attitude that unless there is a compelling reason for doing so, then they will actually not change their gear frequently. It's all about benefits vs features. If a new body does not offer specific benefits to the type of photography one does, there is no value.
For portrait photography, where conditions are often highly controlled, the need to update is much less pressing. For a lot of portrait photographers, there is a preference for seeing their subject through an optical viewfinder - they seem to feel it gives them a better connection with their subjects. I have shot with both and personally find either quite acceptable. I know of several such photographers who keep their cameras for many years (I only recently sold my 5DIII and IV, (with some regret) and I retain a 5DsR (a 52MP sensor camera with the AA filter cancelled to enhance sharpness) - such cameras are built to last and, if they do an acceptable job, then there is no economic sense in doing frequent upgrades especially as the photographers know their gear intimately and trust it. The 5DIII and IV are rather classics in that context.
While the R5 (and now R5II) are extremely capable cameras, they use a different lens mount. So, to gain the maximum benefit one might think that there is an added investment needed in RF glass. This is mitigated by the ability to seamlessly use EF glass via adapters on R bodies with major reliability: but again, for such applications as portrait and modelling, there is no pressing need to invest in the considerable cost of upgrades. That would be less true for applications such as news, sports, or wildlife, where the conditions are not as controlled and moving subjects will be better tracked by the excellent face and eye focusing of the R-series bodies and the in-body image stabilization.
Basically, for professionals, if it ain't broke don't fix it, a camera is just a tool and an expense. Unlike enthusiasts, who often are significant purchasers of new high-end gear: either because they just like technology, like to show they have the latest tech , or believe that the upgrade will elevate their photographic skills or results.
The other factor, often ignored by non-professionals, is that the optics are really more significant than the bodies for many situations. I think most professionals and experienced serious amateurs would agree with me when I say that the investment in glass is often greater, and will likely outlast the longevity of any one body. We would rather have great optics and an older body rather than a new body and lesser lenses.
cheers, TREVOR
The mark of good photographer is not what they hold in their hand, it's what they hold in their head;
"All the variety, all the charm, all the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
