I think the point you're missing is that a picture you take yourself is (at least for me) infinitely more valuable than the same scene taken by another person. After that posting it here and getting input in how you could have done different or better is enough justification to take it. For some people this is a hobby they enjoy That's the reason to take a photograph and why should you have that spoiled by Terence Donovan or anybody else.
Yes, I can understand what you are saying, but that is a different thing to understanding the why
of it. As I said about my own efforts in that sort of work, it was fine as long as there was a financial motivation but it failed utterly to engage me without that.
It's as if there is a sort of need to take photographs and it has to met with something, but therein lies the problem: what is that something when commerce is removed from it or, alternatively, some other valid reason - a social service to the community, perhaps - does not exist? I can't believe that any photographer who has advanced enough to be able to shoot and get whatever he wants still feels the need that you outline in your explanation. Surely there has to be more to it than just shooting something because it's there and you can?
Regarding Donovan, far from spoiling anything for me he simply articulated something I have felt for many many years.
Many professionals go on and on about 'personal' work, but I have seldom met any of them who actually do anything that can be classified as such; for most of them, personal means nothing more than their modus operandi, their style or specialisation which is a place they got to because it represented the sort of work that they liked to do. In other words, somebody into fashion might spend non-assignment time shooting yet more model pics, which could
be described as personal work but is in effect nothing more than an unpaid version of the day-job, a way of getting something slightly different for the book. I am not saying that some fashionistas might not be crazy about photographing sunsets, I just haven't met any of them like that.
For the amateur, on the other hand, it is all personal work unless he is a shamateur on the side.
However, I am fully prepared to accept that it is probably myself who doesn't 'get it' rather than the legions who obviously must.