I was present as this unfolded and I can tell you with absolute certainty that it was the introduction of CRZ that led to the dissolution of server communities. Not LFG–CRZ. A single point of failure.
Again, I feel the need to reiterate this poster for his extremely accurate statement:
I dont understand the logic that this addon will be necessary to find groups. There are plenty of people who don’t use addons, and these forums represent 0% of the population that is going to be playing classic (rounded down) but even still there is clearly enough of you to make a group. Also this addon attempts to use regular channels that people without the addon can see.
It seems really crazy to assume that more than 20% of the community will bother with an addon that does little more than enable grouping outside of capital cities or that even if 50% of the population is using it that it will affect your gameplay in any way. If you want to get groups, play nice and play an active role in your community. Simple.
Well, you’re wrong. As soon as you could be anonymous and be auto grouped with glorified NPCs and still complete content, it started dying. CRZ helped, so did guild perks which created the mega, impersonal guilds.
But it was cross-realm LFG/LFR that really did it.