Hi,
This setting was left for cases when you have only one store. But since you have 6, then this setting is not used. The Google map is clever enough to take all the six shop markers and zoom the map to fit all them in. And that is why you do not need zoom level.
#TOPICS IN DROPDOWN: You can comment the code above and uncomment this in order to have all topics in dropdown!
<div>
<a class="view-all" href="@Url.RouteUrl("ManufacturerList")" title="@T("SevenSpikes.MegaMenu.ViewAllManufacturers")">@T("SevenSpikes.MegaMenu.ViewAllManufacturers")</a>
</div>