When building a platform out a platform, the most important aspect initially is to be able to create core interactions among the initial users. These core interactions make the platform valuable, and vastly increases your chances of developing viral growth loops, as opposed to word-of-mouth effects.

To help you distinguish the difference between viral growth and word of mouth, here is a thinking.
Word of mouth will happen when somebody hears that Mark Cuban is on Clarity and she will tell her friends to check Clarity out; it is newsworthy. You will get sign ups out of curiosity, but those new sign ups will still need to interact within the platform to create value.
Viral growth will happen when users get more benefits by having their own social connections on the platform, and therefore they will invite their friends to join. For example, if Mark Cuban was on Clarity and Clarity was offering a "group chat", a single Clarity user might decide to invite her entire startup to join Clarity, so that each can connect to the group chat with their own accounts and ask questions to Mark. This positive network effects differentiate viral growth from other traditional marketing effects, and viral growth relies heavily on the existence of core interactions in the platform.

Finally, here are tiers of value your producers would create early in a marketplace
Most valuable scenario: You have high-profile producers and they interact. I.e. Mark Cuban is on Clarity and he takes calls and answers questions.
More valuable scenario: You have producers (high-profile or low-profile, doesn't matter as long as they can produce value) and they interact.
Less valuable scenario: You have high-profile producers but they don't interact. In this case, more producers would continue to sign up to become associated with Mark Cuban, hence you get some viral growth. You would rely on your low-profile producers interacting.
Least valuable scenario: You have low-profile producers but they don't interact. This would signal the future demise of the platform unless you step-change the core interaction volume in the marketplace.