Because the underlying operating system, web server and libraries are in continuous flux with security updates. Most of FR is implemented in PERL. Changes to the underlying language implementation and feature support can cripple a large code base.
One of the ugly parts of modern software development is building on a pool of library code from a broad set of contributors. A defect in any of the underlying libraries can break your code. Mandatory fixes to a library can impose a significant re-work of your existing application to deal with the changes.
I retired from 46 years of software development. My project code bases ranged from 250,000 lines of code for a small project to over 4 million lines of code for larger projects. The big ones were spread over 10 different languages e.g. Ada, C, C++, FORTRAN, Java, JavaScript, PERL, shell (Bourne, C, Korn, Bash), PL/SQL, Makefiles and broad sets of newer build tools. Managing the complexity of customer demands as well as security scan demands is a serious amount of work. People who can play at that level and have the security clearances as well are not inexpensive.
Having answered your question, my two "wants" for FR include being able to delete a post I have created or edit one to fix an error. I recognize those are significant tasks as I've done that for my many customers of my career.
I’m a software engineer like you and have founded, built and sold several software companies. My point was that all software can be maintained and extended, even a crusty old pile of Perl scripts.
They’re sensible suggestions. I think the problem with the “preview” page setup here is, it all depends on what kind of endpoint you’re using (portrait vs landscape, screen resolution, mobile or desktop, etc.)
Some WYSIWYG box for putting a post together would be nice - because if I’m writing a post on a phone, having one box with the HTML in it and another with the preview (with the page layout totally different to that of the thread display) is clunky.
Many’s the time I’ve looked at the “Your reply” box and it seems OK, I then preview it, it looks okay, I submit it, read it back, but it looks different to how it was presented in the preview... This is especially the case if I write a post on my phone, but later that day I return to read FR on my home computer - which has an ULTRAWIDE monitor.
The page width on the “reply” screen is set up as if I’m using a 1024x768 display from 2002, but the thread display uses the full screen width. So the “preview” is not actually that reliable for seeing how line breaks and word wrap will render differently.
For fun, put a thread view into https://pagespeed.web.dev/ (which will analyse it for readability and accessibility) - while it scores well on desktop viewing, it falls short on a number of criteria for mobile browsing.
I’ve had to stop using FR in the browser on my Android phone; it defaults to the desktop view which is totally unreadable, and I haven’t been able to figure out how to force it to render in the “reader” mode or a mobile-friendly mode instead.
being able to delete a post I have created or edit one to fix an error.
= = =
delete a post - yeah, but only mine. I have spouted off too quickly sometimes.
Edit a post? That might change the whole flow of a thread. If you make some change in a post that has been already replied to, and you may effectively make those replies not apply any more - or even make them wrong.
Cure - be careful. Or make a new reply presenting the edit or change you want to make.