1️⃣ When you joined the Developer Community and how you first discovered it.

I joined in 2017, and it was by accident.
Looking for help to work around a problem caused by "academic ignorance".
    Some linguistic university experts for German language up in sky, far from reality, decided:
    "S_sharp"  ß (a lowercase only character for hundreds of years)
    will be also an uppercase character from now on.
No one cared about the impact to sort orders, code conversions, pattern match. regular expressions, ...
My cry for help:
German collation of ß in upper and lower case
In DC I got help and advice within a few hours on how to escape
until a new release or bug fix might have an official solution.

Exploring DC was another big surprise for me.
It was rather similar to a proposal I had done in 2005
and  I was massively pushed back by service managers at that time.

DC covered and extended my basic intentions
I fell in love immediately and still feel like a proud grandfather
observing his successful growing grandchildren.

2️⃣ A meaningful moment or story from your personal journey here.

It was somewhat longer than a moment, though just a single trigger.
The challenge was to start working with Docker in some OEX package
Before that, I was rather resistant to publishing complex examples.
The effort to describe a complex setup and not having control
over implementation was rather significant.
With Docker I had a reproducible environment and no traces or remaining
junk after termination.

Another extra was learning to produce videos of my examples for contests.
I never did it before and still don't have any private videos on Youtube.

3️⃣ An article, question, or discussion you consider especially valuable

There are two recent articles that moved me most:
The Wait Is Over: Welcome GoLang Support for InterSystems IRIS + followers
and
Reducing the Footprint of the Docker image of IRIS Community Edition

It's 2 times the same authoring engineer, and what he presents matches my
personal understanding of what quality software system engineering is like:
- precise and detailed analysis
- detailed and fully through tested code before release
- 2 top-class projects

My personal sorrow:
There are groups that may force out the results just because of the
"NOT INVENTED HERE" mentality in some areas.
I speak based on personal experience after being attacked following
a backport of %JSON classes to Caché some years ago.

Pre-Xmas in Vienna

You got the point.  Before means "before this century" 
before CSP / WEBstack, .. were introduced 
There were INT routines in %SYS with lots of $ZU() and $VIEW(). Device 63 was quite busy. 
Most are unknown today. But some are still around and still work.  
It's not as rigid as GlobalDB was / (is?)  but has some similarity.