I understand your pain, but I think the solution lies in the problem. The problem is small tribes with little activity, and the solution is increasing activity (since you can't increase tribe size yourself). You start out adding more content to the Dota2 tribe (and post those to gaming and dota2 every time) and eventually someone visiting the gaming tribe might see quite a few dota 2 posts. They will either follow you, or post as well. Because if someone new comes and sees that there's no activity in dota 2 (because you never posted anything) they won't post either. However, if you post, even if no one responds, it might drive up the incentive to post later, when someone finally visits the tribe.
I was on voat quite a bit earlier than most people, around 4 months ago, so I and others there have talked this problem over many times. Just make sure the semblance of an active tribe is there, and if you find someone saying something in an unrelated tribe like "I remember last week when I played dota..." you suggest they post in your tribe or something. Growth needs to start with content (which is why I've started posting things I normally wouldn't per se, like this news post about the Egypt/Gaza border opening. It might not help me per se (I get my news elsewhere, I usually don't like crowdsourced news since it can often be a lot more biased than any one news source) but if other users come to snapzu and see that /t/worldnews is active they might stick around and also post elsewhere.
Sorry for the rant and the disorganisation of the comment, it ended up longer than anticipated ;)
I understand your pain, but I think the solution lies in the problem. The problem is small tribes with little activity, and the solution is increasing activity (since you can't increase tribe size yourself). You start out adding more content to the Dota2 tribe (and post those to gaming and dota2 every time) and eventually someone visiting the gaming tribe might see quite a few dota 2 posts. They will either follow you, or post as well. Because if someone new comes and sees that there's no activity in dota 2 (because you never posted anything) they won't post either. However, if you post, even if no one responds, it might drive up the incentive to post later, when someone finally visits the tribe.
I was on voat quite a bit earlier than most people, around 4 months ago, so I and others there have talked this problem over many times. Just make sure the semblance of an active tribe is there, and if you find someone saying something in an unrelated tribe like "I remember last week when I played dota..." you suggest they post in your tribe or something. Growth needs to start with content (which is why I've started posting things I normally wouldn't per se, like this news post about the Egypt/Gaza border opening. It might not help me per se (I get my news elsewhere, I usually don't like crowdsourced news since it can often be a lot more biased than any one news source) but if other users come to snapzu and see that /t/worldnews is active they might stick around and also post elsewhere.
Sorry for the rant and the disorganisation of the comment, it ended up longer than anticipated ;)