In VP, heavy tribute is absurdly strong
Welp. It's time to nerf bullying... Joke aside...
What you have said are some very interesting ideas. I've learnt a lot from you. FYI, just to let you have a basic idea of my skill level, I have no trouble in King but sometimes struggle in Emperor. Difference between experience and skill level can really differ perceptions.
Okay, back to the topic, garrisons aren't free, but they can provide slight protection to cities. I don't need more soldiers than it is needed to destroy barbarian camps or travel to far away land and leave my cities behind. Also sometimes it is just too far away and it is better to leave the camp for others, which can be nuisance for them.
It is difficult to say as I had only a few games start with the left side. The production from border expansion seems to synergize better with settling culture bonus. Still, yes, you don't get the juicy bonus before Imperium, but the first couple of settled city can make a monument, a shrine, and a whole bunch of other things. I don't mind missing one or two technology if I didn't have the time to start up my production engine. I just simply can't afford the production cost.
Also, the right side aren't doing nothing either. First, you send out raiding parties killing camps, after a while, when there is no more camp, some of them go back to cities and become garrison. Meanwhile some of them will continue their job, I build units that I needed to defend my cities, to become garrison.
EDIT:
@pineappledan You can bully multiple city-states. I have to admit it, rewards from cultural City-states are no kidding. It is around 150 cultures when you unlock the 3rd policy.