The short answer:
Collecting resources such as sandstone, silver, copper and such DOES help the guild as these are required by the architect of the guild to make into building components, such as braces and bricks. Each building, wall section or other city item takes a good number of these building components to build.

The long answer:
At level 40 you can collect the first tier item and the corresponding rare, such as copper and tin, or sandstone and clear quartz. Higher resources require both you having completed the collection quests and your character being of appropriate level. From what I can tell each high resource is every ten levels, so at level 50 you can start the Yew collection quest etc.

The first tier city items take first tier resources to build. Second tier city items take a higher number of resources in general, and I believe they also require higher level resources, possibly including some of the rares (such as tin).

The one chokepoint for our guild is not the resources as much as it is the MONEY for the architect to buy the appropriate plans that allows him to convert from resources to building components. Depositing money into the guild bank will help the most at this point, but in the long run we also need multiple players able of collecting the resources for the higher tier city constructs down the road.