This is difficult. First, let me say that I do not subscribe to the 'leave it be' theory.
I enjoy seeing the works of art that people create, and, indeed, do so myself, (although I am in no way an artist other than the p... type!) albeit without the results we see on the forum.
I think there is a line, a hazey line, between producing a pleasing, or good photograph, and the heavily modified work of art. Both are valid, and have their place in the order of things.
I can give an example of a set of photograhs a friend took in the Yorkshire Dales. The 'stock' landscapes were excellent, full of cloud detail and copybook compositions. They had minor corrections, but in every respect were 'records' of the scenes. Selected images then had the full works applied to them, and were amazing, but were not photographs of that place. Almost every element of the original had been changed. The more than adequate sky/cloud detail had been changed, colours were different and sections had been removed or added by pasting.
I have no problem with this, but if they were going to be shown to someone as 'Blueberry Hill', or whatever, then it seems a bit fraudulent, as anyone visiting the site would not be able to see that scene. It only exists in that picture. The clouds are probably not too good an example, because they do change regularly, but the way the skies had been altered, although brilliently done, were un-natural.
Many years ago I was chatting to an artist who was painting a street scene in a village where I was taking photographs. "The advantage I have over you", he said, "is that I can choose not to include that lamp post, or telegraph pole in my picture, and my picture will be better for it". Good point, although now, I can also have that option.
Here we come full circle. The heavily modded picture is, in essence, the same as the artisit's picture. It is no longer a photograph.
Having now had to focus on the topic in more detail than I had done previously, I can now answer my original question "do we do it to excess"? The answer, as you correctly said, is "No".