Well there's a few things they did wrong. Personally I think the following things are needed to form a well run empire:
- You need a nice public face for your empire, not someone who can't even type 5 coherent phrases in english. Take the posts of Mirgorod as an example, they might not be in perfect English but you can always understand the point they are making and there's no horrible leetspeek involved.
- Batshit insane shotgun diplomat, this is a requirement for any village. When someone takes something from you the nice guy approach is futile, even backwards, especially if you are the stronger party. What you want then is someone who can literally reach trough his pc and strangle the guy on the other end. I've seen those discussions before, they are all awesome. You go in full offence, dazzle your opponent and then get what you want without bloodshed (depends on how strong you are obviously, if you're perceived as weaker then you'll probably need to back your threats first).
There's no doubt in my mind that this is one of the most important figures in your settlement. - economic powerhouse, generally the way you are going to bind those other villages to you isn't via force (lol brick wall and then what are you going to do? hah!), it's via the oh so sweet carrot that is high quality items. It's very easy actually. You start of by creating a high quality center in a safe spot. HQ kiln/smelters access to mines etc. This is where you create the bonds with your subject villages. They'll come to you for thanes, seeds, swords, barrels, churns, tanning tubs … you'll need to be able to provide them from your main village. If you are able to do this they won't break loose, because they'll need and want your items. If you're generous about this they might even start to like you!
- trade!, start building trade relations with other powerful factions to import items you can't make. (say for example, some hq cast to make an anvil/hammer, or hq bricks).
Now what you want to do is make sure that all the trading happens via your town, and your trusted traders, so all the towns you control are directly dependant on you and your relations. Try to make intra town trades as well, troughs for hq milk, metal for chants/bulbs… Trading is a good way to form relations. - chat, your empire needs and irc chat channel and it needs to be frequented by most members. without it it won't work.
- mad grinders, you'll need a few of those. You'll want to be able to at least process everything but hq rings. This means a farmer nut who skills up crop (fibres and wheat really need to be above 200 by now, if you don't have this then you should start looking at trading for them). A sewer/silk guy (200 sewing/dex/later on psy) for farming hats merch robes and other toys to keep subjects happy, though I'd go for multiple silk makers at start, you'll need tons of it at first. A tree guy (carpentry/farming 100+). And then finally a couple melee guys (200 surv, melee/agi/str/con etc).
most of these can be combined though, it's just easier to start of with a few specialists and then end up with multiple people who can do a lot of the above actions. - mines, access to bronze is a minimum requirement. Bronze is the best metal anyway unless you are in a very well organised village. Later on you'll want to get an iron mine to make steel. It might be valuable to have a silver mine but I'm really not convinced of it's usefulness the good things need gold anyway. there's only so many thimbles (though they are nice to wear while farming) and forge rings you need.
You can actually make as many threats on the forum as you like, people soon enough realise what kind of person you are. If you're generous and calm with them when it matters than they'll appreciate that. It's better to keep a few friends in your subject villages and have 1 less strength or psy if you ask me. The first few weeks all you are going to do is skill up, build your town and search for quality spots anyway. I don't see how you could start subjugating people before your basic town is up and running.
What toh really did wrong was the lack of good PR, as far as I understand it they only really got people without metal to join them, so they should have been able to bind people to them. Perhaps they should have grinded melee a bit more instead of talking big in the forum?

Or at least trade for a couple nice sets of equipment.