A read-only link per client, and no seat to buy. Every site can hand out share links that need no account: the client opens a URL and sees the dashboard, and nothing about your account is reachable from it. The link can be revoked in one click, and it can carry a password if obscurity is not enough for that client.
The link is named, and the name is what they see. Call it "Client: Acme" and that is the heading of the page they open. It also carries the time zone of whoever created it, so the numbers they read are the numbers you read. A period means different days in different zones, and a report that is silently a day off is worse than no report.
A digest that arrives on its own. The monthly email most clients actually want, sent on a schedule, with its own unsubscribe link.
Team access when a link is not enough. A client's marketer can have View on their own site (the statistics and nothing else) or Manage if they change settings themselves. It is granted per site, so nobody sees a client they are not working on.
No consent banner to negotiate. Nothing is stored on the visitor's device by default, so the conversation with a client's legal team is usually one sentence long. That is often the reason an agency looks at this in the first place.