Few users of reddit communities are dedicated enough to that community to be willing to use it via an app that doesn't aggregate their interests into one doom-scrollable UI, much less donate to a site for hosting costs to keep it afloat.
99% of phpBB installations were pwned and distributing malware. It’s a terrible model. If we want small distributed operation of software like that we need a revolution in software operability and quality.
It's not hard to to write significantly more robust software than what you get on a late '90s LAMP stack. What killed those forums was the constant upkeep needed to keep them secure. Most of that is historical baggage though. The software emerged in a time when the threat landscape was completely different, and things like data portability wasn't even a thing.
The problem that remains is spam mitigation. Bots are very hard to detect, and there really aren't any good distributed approaches afaik.
That's one of the reasons centralized model works so well nowadays, nobody wants to take care of things anymore, self hosting your own apps is becoming a small niche
> ... nobody wants to take care of things anymore ...
I mean, why would you? It is quite a bit of technical hassle, even for an experienced admin. There's quite a bit of cognitive load just deciding what software stack to use, even before you run an installer. And then you have to maintain it too!
Compare that to less than 3 minutes of sign-up and creation of a new subreddit. It is an orders of magnitude difference in effort and knowledge required.
You're talking about late 90's-early 00's tech there (basically, LAMP architecture). It wouldn't be that hard to develop an open source, generic hierarchical forum engine that would be easier to deploy than an Apache+PHP+MySQL suite from scratch (on a dedicated Linux server that you have to completely configure all by yourself), and that would work both on a web browser and through a smartphone app.
Security would be less an issue than back then, too. We learned a lot since early PHP and early Javascript's bad practices.
I'm lucky enough that my main hobby's primary discussion era is an old-school phpBB, and it's likely not going to migrate to Reddit or Facebook or somewhere else. It's great. Content is fully indexed by search engines and can be easily searched using those engines. Decades of FUD from cloud providers and centralized services have convinced so many that hosting your own server is difficult and expensive and scary and just not something normal people do. Online communities really need to get back to self-sufficiency.
I flip between Flask and Django depending on what I'm doing.
If I want to make something "from scratch" I do it with Flask, if I've got an existing database (or something that can be wrangled into a database) I do it in Django.
There’s literally no reason why not and it’s never been cheaper to run