Not that BBS history isn't notable. I'm just saying it would be wrong to delete it even if it wasn't.
The "aha" moment with Wikipedia is realising that it is not an archive (which is what some people want). It summarises archives, of course, but the point is to write a compendium of useful knowledge.
Where to draw the line is not easy; I think we are too heavy on the notability front. A better way is usually to think "how many people would find this useful or interesting", and if it is a reasonably significant then it is worth writing about.
The culture is a monolith and can be hard to break into - I've long moaned about that. Changing that is hard; I don't begrudge people moaning or criticising it, but I suggest that the most constructive approach is to take part and bring some common sense on board :)
Just don't get sucked into the politiking and game mongering.
And the notability argument is that you can already post an article about that tree, on the larger internet.
This argument doesn't seem helpful. All of those problems will continue to exist regardless of whether some articles pass the "Notability" requirement or not.
It's a purely external reasoning: wikipedia as I see it is already in a un-maintained state for many not notable articles, more articles without a change to how WP works will lead to more of those diminishing the overall quality of the project.
And no, I don't buy that not deleting articles will magically increase the number of contributors.
You know, if you let everyone use the Internet, the average quality of the writing will go down!!!
The average is completely the wrong metric to be using here. Not as good articles do not 'infect' the good articles, and the average is meaningless. If you don't need to know about a topic covered by an article you disapprove of... you don't have to read it.
I am not a wikipedia editor and am not defending strawman deletionists, I am only giving an opinion based on my daily findings of broken links, flags raised years ago and never updated, missing links between languages et cetera.