It's not about ease of publishing. The issue is what people get in return for publishing. Until you can design a platform that gives top creators as much money+attention as commercial platforms, you'll see a drain of top creators and their viewers to commercial platforms.

100%. You don't even need to give people money. It's about attention and feedback.

People post photos on Instagram and status updates on Facebook because their friends will see it there and give it a thumbs up.

A couple of decades ago, I spent a lot of time laboriously building a website for scratch for my photography. It was objectively a really nice site. I had my own domain, hosted it on a VPS, and put a ton of work into the layout and design.

But none of my friends ever thought to go there. I could see by my web stats that every now and then a random stranger would find the site... but they had no easy way of connecting with me and acknowledging that they saw it. If they put a lot of effort in, they could find my email address and email, but that's a hell of a lot harder than just clicking a little thumbs up button next to a Facebook post or filling a comment in the comment box.

Uploading photos to my site was about as rewarding as printing them out and throwing them in the trash. I thought about adding support for that to my site, but then it opens the whole can of worms around user-generated content, abuse, moderation, etc.

Eventually, I moved to Flickr, which at the time was an actual community that gave me that connection. Then Flickr fizzled out. Now, on the rare times I bother to process a photo... I just upload it to Facebook because that's where (a dwindling subset of) my friends are.

It's not about the content. It's about the human connection. A CMS won't fix that.