Indeed. These days we have 24x7 net connections on both our mobiles as well as home LAN/desktop whatever, but you still can't get a single, 1-click, drop-dead simple program that you can use to both author as well as serve web-pages and images right from your own device. Thanks largely to dynamic IPs, NAT, firewalls, ISP upstream throttling and developer apathy (since their livelihood may depend on the complexity of this), Joe wanting to publish his thoughts or photos still either has to sell his soul to FB/Insta/whatever or fork over significant cash for the likes of Wordpress/Squarespace, OR spend days to teach himself the nitty-gritty of buying a domain, fiddling with your DNS, setting up dynDNS, connecting all this to GitHub pages or whatever, fronting the whole thing with Cloudflare.
Exposing your home devices to the internet is a really bad idea, because it exposes you to doxxing, DDoSing, whatever security issues your 5-year-old smartphone may have, and a plethora of other risks.
People used to do this in the 90s and early 2000s, but it turned out to be a hilariously bad idea security-wise. Even the enthusiasts these days use a dedicated server somewhere in a datacenter. Services like Github Pages and Cloudflare exist for a reason, and it isn't because anyone is trying to gatekeep web hosting.
Some of us have been doing this since the 90's and don't see and end in sight. The issues are not bad compared to your average customer service call. I prefer knowing what is going on with the technology I manage. Most websites are way over complicated on the backend. It's very easy to self-host.
Other than DDoS, all other issues you mentioned apply equally to all internet facing apps like Whatsapp etc. A static file server can be hardened to the point where only DDoS remains a significant threat and that hardly applies to an average Joe. IF my little site of a few boring pages & pics gets DDoS'ed, then I can move to Wordpress, Cloudflare or whatever.
There’s also a nice middleground - you can just proxy your site through Cloudflare. This masks your IP and protects against DDoS, the only caveat being you need to move your DNS to Cloudflare.
My usual model is to configure the servers to be hosted locally and rsynced anywhere else. I'm currently going through this exercise right now. I start by making everything good local and then can publish anywhere.
I love having a completely independent working local copy. My environment is perfect for my needs or I change it.
Basically my deployment plans and disaster recovery are indistinguishable.
This isn't the only reason. People who are trying to get attention will flock to where attention is directed. For better or worse, centralized platforms are a good place to do that. It's the same reason protestors, charity drives, people handing out free tickets to a new concert venue, do this in downtown parks and public squares, not their front yards. Popular photographers hold shows in galleries, not their own living rooms.
