@Killerfurby33 & @Deus ,
I like both your points on this and i believe i have a solution: <b>Scale (Material Gain) vs. Completion Time (Action Time)</b>.
Okay i'll further explain: Say you want to start harvesting resources i believe it could go like <b>A:</b> Solo: you find a spot within a designated mining zone and set to work. The amount of materials harvested and the time it takes would depend on the individual skill level you have in those actions. <b>B</b>: Group: the combined skill lvl's of those working in a 'team' would enable the effort to yeild more of something, more quickly.
I feel this approach would both satisfy the 'Soloist' and the 'Groups' by enabling someone acting independent to still be able to do things for themselves without depending entirely on others, thus the increase in specific skills would show greatest results. At the same time, if you were in a group or 'team' their combined skill levels for a given action would have as much (if not more) weight to it that the specialist acting solo, thus enabling those that don't specifically want to specialize in a given skill to still collaborate with others to achieve the end result of gaining resources at a given pace.
This model would allow for specialists to act independent where they wished but also reward collaboration of individuals working together for a common goal. Given that, the specialist would still be valued / requested to work in 'teams' by others as their 'weight' of skills would increase the over all production of materials greatly, even more so if it was a 'team' of all specialists acting together (as this would have the greatest effect of the combined skill levels). I can see this being extremely present when the infrastructure of a given operation (i.e. you develop new mining equipment, well its going to take a certain skill level to operate it) requires those specialized (skilled enough) for certain aspects (i.e. operating cranes / loading equipment) and those not so specialized (but still needing that resource) (could be the haulers / miners (especially if stats are worked into this (i.e. more str over dex or int where required and whatnot))).
This would also make sense for storefronts and trades where someone not wanted to devote any skill points to the given actions could trade for materials / labor of those that do or could produce.
This same model could work for projects such as building a house. As you mentioned, as an individual you could acquire the necessary materials from storefronts or other individuals without having to harvest (or needing the skill to do so) and work on building your house yourself. This way will take longer because... well, your building a house without help, it just does. OR if you had multiple people helping out it wouldn't take as long to do so because well more hands working on more than 1 thing at a given time just makes things faster. (Again if a 'team' was formed and you utilized the combined skill set of those collaborating it would overall be greater than the individual, but not outright required).
This in my opinion would be the best way to go for Skill mastery / Collaboration Control / Resource Harvesting / Project Planning, where when available a specialist could fill-in on given works in progress or resource gathering adding their 'weight' of skills to the mix and where such requirements as skill levels exists, yet also allow for those not specialized to the same extent the ability to complete the same works and harvesting by working together as a collective unit.
This would both award the Soloist who wants to specialize, and the Grouper who may not be specialized in the right skill for the action required, to both work at their own pace and desired skill sets without being impeded by lack of labor or skill. At a given time, the individual could participate in the collective effort, or focus on personal gain without falling to far behind the rest. Of course the more people work together the better, but you can't deny the individual whim.