Audiences come from the CRM, not from a CSV
An audience is built over the contacts and customers already in the system. You do not export a list, upload it somewhere else, and end up with two versions of the same person who unsubscribed in one and is still subscribed in the other.
When a contact changes in the CRM, the audience sees it changed.
Campaigns and templates
Campaigns are composed from reusable templates and sent to an audience. Because delivery uses the same email infrastructure as invoices and notifications, your domain reputation is managed in one place — not split between two services that know nothing about each other.
Your own affiliate programme
You can run your own programme: settings, campaigns, partners, a commission ledger and payouts. It is your programme with your partners, not a network you join.
Worth knowing
The most common way to ruin a contact list is to keep it in two places. Unsubscribes, address corrections and consent have to be true in one place, or they end up true in none — and that is a compliance problem, not merely an untidy one.