For the least subtle take on this possible, see: https://youtu.be/mj5IV23g-fE
So should people not be allowed to write on a personal blog or in an online publication for the public exposure/other knock-on effects relevant to their day job? Because all those people are, at some level, competing with freelancers and other writers.
(I've actually had conversations with professional writers about this. Their general take is that ship has sailed.)
Now, to be clear, organizations trying to get you to do something that you're typically paid to do is absolutely a pox. But there's a difference between a consultant being asked to give a free presentation at an event "for the exposure" and doing so voluntarily because they've made their own decision that it's a worthwhile investment in lead generation or whatever.
To give a personal example, last year I published a new edition of a book. It wasn't for free but it might as well have been in terms of earnings per hour, but I actually wanted to do that. But if you want me to write something for your corporate blog, you're absolutely paying me and paying me pretty well.
It's important that we not allow our moral judgments to interfere with the facts. This is obviously false.
And should a consultant not be able to maintain a blog that people don't pay for because doing so competes with freelancers?
I think it absolutely does increase that tendency.
When I write for online tech publications, at some level, my writing, for which I'm not paid, takes money out of some freelancer's pocket--all other things being equal (which of course they aren't).
And all the people who speak at events for free and even cover their own travel (or their companies do) definitely make it harder for qualified people who would prefer to be paid to do so.
But, to be blunt, I don't care. If it's in my personal interest to do those things for free, I'm not going to choose to abstain because of some microscopic impact on the labor market.
In this photographer case, I actually don't think there's much of an impact. Someone mentioned Super Bowl performers performing for free. I doubt anyone thinks Lady Gaga is going to start giving gratis concerts all over the place. There has been a major impact on photography as a profession but that's more about the proliferation of free, cheap, and easily obtained amateur photos.