Growth for growths sake.
Not just at a platform level but at a community level too. Around 6 or 7 years ago I started to really notice people talking about growing their subreddits, making changes and tools designed to increase the subscriber count.
For what? There's nothing to gain.
The main subreddit I modded finally became impossible to moderate for quality when, despite our lack of "growth strategy", the influx of new users became too much for the communitys culture to persist and it slowly turned into a lowest-common-denominator topic-flavoured meme ghetto. And from the outside I saw many of my favourite subreddits fall to the same scenario.
So I would say, we should avoid or rethink the idea of growing lemmy for its own sake. Eternal September will come eventually, lets not rush it
I remember Armagetron always getting fired up at LANs when I was at uni, 2005ish