It most certainly
can be made easier, where "easier" means "more easily achievable by a variety of people, some of whom are not as technical as others".
I could code this feature myself: you click on a button like "post an image", and you can upload an image from your computer. I would enhance it using the HTML5 drag-and-drop API. I'd offload the image processing to a queue like Iron.io and probably store the result somewhere else, like a CDN, or Dropbox, or maybe even Flickr, namespaced under your user account for administration purposes. After all that, I'd smile a big, smug smile and go back to lapping my bowl of cream and preening my whiskers.
You could still keep the "post an image from another website" option as well.
Whether it's practical is a very different question. It could be too expensive. It could be too much work. It could be too fiddly to integrate with the forum software (which is notoriously difficult to work with).
A common pitfall of being technical is that you fail to understand less technical people. You only appreciate this when someone more technical comes along and does the same thing to you.
Allow me to demonstrate:
Say you have a website and you update it occasionally. You use an FTP client to copy the files from your computer to the web host (which is how most people do it).
Now let's say I run your web host, and I've decided that FTP is an inferior way to update your web site. I could say something like this:
I'm sorry, we've discontinued FTP because it's a rubbish way to manage your website. Instead, simply SSH into the server, init a bare repo and Git push from origin. Set up a post-receive hook to checkout your master branch, composer install & dump-autoload, and you're golden. It's much easier.
This is (more or less) how I manage my website. And to someone like me (today), it really
is much easier. I can't understand why anyone would want to manage a website by uploading the new files.
You mean they don't even use version control? Madness!
But to most people (including past me) who have a website and want to update it, this process is impossible to understand, let alone implement. They would have to learn so much techy stuff that they really don't need.
It's not a perfect comparison, but maybe it can help explain how it feels as a less technical person being told by a more technical person that "it's just as easy the way I do it".