You make a good argument for not using free photo-hosting sites!
If organization is the reason to use a photo-hosting site I can't see how it is useful to me. I already organize my photos into albums on my local drives and can very quickly find any photo and view it with a click. When I want to use one in an email or document I can copy paste, drag and drop, or "insert image" and for forum use I can upload with a click. I can also view, organize, create documents, and otherwise use all the photos without internet access. An example: I sometimes start a woodturning demo with a slide show - with my laptop I can prepare the pictures in the car or anywhere. Before I post a photo I usually spend a few seconds to crop and edit as needed and reduce the image and file size to make it internet friendly - I save the smaller version in the organized albums ready for posting. This is all so quick and easy: as my piano teacher was fond of saying, "everything's easy once you know how."
I don't use a link to my photos on a forum since, as you well described, linked photos can disappear without warning. Even photos linked from a person's personal web page can disappear permanently if that person quits maintaining the web site or passes away or something. Some archived messages and threads are almost useless now because of dead photo links.
The over-riding point for me is putting photos in someone's hands removes the control from mine. I keep nothing in the "cloud". A server crash, a natural disaster, a computer hack, a hosting service mismanagement, or as discovered, a sudden change in policy and business model can cause instant loss - all without warning. My personal photo archive is important to me and I want to keep control in my own hands rather than the mercy of others. Having relied on my data for my living for 30 years I trust no one and backup everything myself to multiple storage devices. (Macrium Reflect is incredible) Something my mother said applies here, at least for me, "if you want something done right, do it yourself."
BTW, there is nothing that guarantees that any forum, even this one, will be here in the future. I know from past experience that providing a free public forum is not free! Without a wealthy supporting benefactor each site has to pay for itself. I personally support the forums I frequent with my $$ even if they don't require it. Some, like SMC, have distinct advantages for contributing even a tiny amount, they ask just 50 cents a month here!
http://www.sawmillcreek.org/payments.php I'd feel a big loss if one day SMC and the entire archive of messages (with photos) suddenly disappeared for financial reasons.
JKJ