It was like this until the TC patches, since then everything changed. At one point we no longer could log out boulders on free to plays or mail them, etc. so we had to figure out different ways. Some were visible still, but not all. My guild would bring all the boulders with us for a siege sometimes and so there was no noticeable prep.
Being in Imperial Dreams I've done many seiges, we were probably the best known ninja sieges in MO and very much wore that title with a badge of honour, didn't bother us at all. I've sieged from small houses to big keeps, and I have been on the end of both scenarios too. Pre TC/F2p/Molva's/bags was probably the hardest in some ways as far as logistics, we just had lots of players who had several accounts so this was ok for us.
Post TC/F2P/molva/bags was probably the easiest logistically until they limited F2P's holding boulders and added a weight or boulder limit if I remember correctly stopping bag stacking, then it bascially went back to the previous situation only with alerts from TC if I am remember that right which was useful.
The balance issue was never the "knowing" of an attack, honestly that stuff just works its self out, I'll explain in my experience how this tended to work in Mo1, and I believe is logical to assume will work the same in Mo2.
Invested guilds Awareness(guilds with assets)
If you have assets, you know you have to protect them, if its small stuff, you tend to find friends in the area and make some kind of non destruction, non aggression, or stright up defence/ally packs with bigger guilds close by.
Honestly, I can't remember a time where any sensible guild didn't know the names of people in their area, you couldn't so much as fart in somebodies territory without them knowing, things like "huh somebody has just hunted here the bear spawn is out of place" it was common practice to not shoot stuff if you were roaming so you didn't give away your activity. You would notice your rocks being mined out, or just stright up different names. Your area is a familar place to you so that is the first sign something is up. Mo2 will only have single characters per account so this will make it even harder to smurf your way in.
Point: Guilds with assests were onto it, you just knew your area, traffic norms and everybody had allies or pacts. And you had phone numbers and FB groups or whatever alert systems to get the whole crew on who normally were already logged off in a certain spot ready to rock with a plan.
Invested guilds behaviour
Most big groups, either a single guild or more likely an alliance with assets actually didn't war with each other very often. If two opposing forces did, they often were not actually the main aggressors or instigators. Factions would sit out of a conflict, and only jump in when they felt it was a sure thing, and they were safe enough from retalation. Even orchestration was rare, like MO politics becomes very very deep and rich fast. If a big group did want to start something, the seasoned ones would find smaller groups who were fired up against their enemy and fuel that on and often start to back them with equipment and money. However proxy warfare was risky, If a big or key guild were found out to be orchestrating smaller groups as they were at war with the most prejudice against them. This would resault in full blown warfare that normally actually meant the end of both groups assets because there were often hidden cost and compromises to this kind of strategy.
Smashing a groups assets and tearing down a keep normally meant one big thing, you just guaranteed a whole bunch of people who will always be on the opposite side of you until they get their revange on your stuff. There is an even more sinster deal you make with the devil however, those little groups you just banded together, funded and aimed at your enemies ? You better keep them happy, because now you just got intreached with a bunch of guys who are now experienced and capable at siege warfare with nothing to lose and a big short list of people they can call apone to attack you to boot (the people they just blow up). Very season politcal groups were careful with mastermining destruction because the more guilds you involve both sides the more chalances of sideway results, but if you can handle it yourself its a strong look but less messy with future issues
Point : Don't throw rocks in glass houses. Everybody with assets is tied together in a web of action and reaction and consequence.
The balance of those with nothing
Balance of those that have nothing to lose, no assets or skin in the game, against those that do. The balance in TC kinda went sideways when TC stuff cost time and effect compared to the cost it took to destroy it. One cata with the most basic logistics could do very good economical warfare in favour of the attacker.
I have been on both sides of the fence here, extensively. I won't ever complain about our stuff getting blown to high hells from a guild that had nothing, because we literally carved out our reputation for being the group you knew would ninja and blow apart your assets if you messed with us back when we had nothing (I think we were the first group to ever ninja down a keep solo in less then 50 minutes) and were not the best fighters so our threat to you was our ability to take. When we had nothing we were ruthless, when we had assets we were still deadly with that, but we eased off using it as our main weapon and only did enough to maintain our repuation or when the bridges of politics burnt down.
Point: Those that have nothing have to be kept in check in some way, its not to say the faceless don't have a role to play, to be funded and use their advantage, but there has to be a link to those with something (such as funding) or a natural logical barrier or disadvantage to some degree.
