I have to admit. It’s not difficult to use an image hosting site. I did that for over a decade on here and my posts were very picture heavy. And it’s even easier now. It would be interesting to see how many members actually have a problem with this though.
This topic has come up on Dreamwidth, a really nice independent social media site. Whenever bad stuff goes on on tumblr everyone will say, 'let's all move to Dreamwidth!' and nobody ever does. Part of that is the network effect that everyone wants to be where everybody is, but a big part of it is that Dreamwidth has sensible hosting budgets and Big 4 social media does not. Consequently, image-driven and video-driven social media has become a norm and an expectation, backed by venture capital, that's super resource intensive and now entrants can't compete with.
So that's issue one: there is an expectation that images are central to the internet experience, including image posting privileges. It's almost like language in some way, a picture is worth a thousand words.
Issue 2: Internet skills from about 6 years ago, you cannot take for granted that younger people have them. The modern internet is all about reducing friction, and even a modest quantity of needing to learn an interface is a barrier. So yes, it's not that difficult to get a hosting provider for images - or use markdown in posts - or use an rss reader - or switch to mastodon instead of twitter - or use forums - but most people will not do it, for whatever their reasons are. There's a very real barrier, something to do with effort. I don't mean that in a disparaging way, I mean that big social media creates this effortless, frictionless, dissociative space, and it's a learning curve to approach computing in a new frame of mind.
(you will not believe the fuss people in my life make about sending me sms messages or using Signal, they want to use WhatsApp. Texts are exactly the same as WhatsApp. But they will not send me texts. They want to WhatsApp me. This is what I mean about people being used to absolutely no friction. The additional life friction of opening up your texts in their smartphone is too much.)
Related to that is the problem of forums, basically, because when you come here you have to read what other people have written, consider a reply, write it out, and build relationships over time. That's all very 'effortful'. And a lot of people's Internet time is more like napping in front of the telly. In short, you dont just need to persuade people they should be on bushcraft UK, you also need to persuade them they should be on forums full stop.