I've been participating in numerous online discussion of specialized in-depth subjects, work- and hobby-and social-related, for 30 years, long before the existence of the Web.
Web forums (based on the original Usenet model, before it became commercial) were explicitly designed for this.
Facebook is an extremely bad choice for information sharing on focused subjects, putting aside the fact that many online users boycott it due the crass commercialization and random functional changes. There is no "thread" concept, alerts cannot thus be made thread-specific, or fine-tuned for getting a per-new-post/per-day/per-week alert; searching is nowhere as deterministic; there is no convenient way to "pin" posts so that they are always visible (e.g., FAQs); the UI is designed to always show only an initial small part of a post, so you see lots of posts at the expense of a linear-chronology deeper view. It also shows only a random subset of posts, to force you to interact with the UI. Directly quoting from a senior FB developer some years back, it's intended for "very shallow content to be browsed quickly, not read in-depth, so the viewer stays on page as long as possible. Basically, promote a type of ADHD".
That's not how to best serve the interests of a subject-focused community.
Most Forum software is designed to easily allow various views of the posts, and facilitate full ,multi-criteria binary search ("all posts by user ABC with the words DEF and GHI in the subforum 'aftermarket accessories' in the date range MMM to NNN").
FB doesn't have any Customer Service as such. Whereas the way independent forums are administered varies greatly, depending on the subject and personalities involved, in most cases they are fellow enthusiasts like you, so there's some basis for trying to convince them to change policies or technical matters (size of photos that can be uploaded etc.) You have zero leverage with FB, whose actual policies and reasons for doing anything (like removing a post) aren't transparent, and virtually never explained in detail, and the asymetry between any user or group and FB as a corporate entity is much greater.
There are also potential legal disadvantages:
While FB change their Terms of Service, AFAIK the following still applies: Anything you post publicly may be used or reused by any FB user without permission or royalties -- for example, if you post a design for a neat widget to get feedback, doing so will kill any legal rights you have to get royalties on later use. FB does this because they don't want to be bothered adjudicating between members -- understandable with a couple of billion users.
Most Web forums have a much friendlier attitude & policy. Many also use unpaid-volunteer peer moderators to help discussion stay on-topic, and maintain reasonable standards of behavior; this is very evident in the enormously better signal-to-noise ratio.
The concern about backups is valid, but frankly, although FB may invest a lot more in IT redundancy, security etc., they're also a huge target for malicious actors, whereas any given forum at most gets the occasional spam wave. It's virtually always not at all difficult for whomever administers the forum to get some good, free advice from forum members who are IT people re how to handle backups and so on.
I can't think of a single advantage of using FB for this type of thing... I certainly won't participate in any such discussions on FB.