Many websites do double duty.
Usually, they are there primarily to help generate new business.
But they are often also there for existing clients or customers - to provide service, or to generate repeat business.
In planning a website you need to consider which is more important to you and to plan it out so that the site gives the proper emphasis to the major purpose without neglecting a secondary purpose.
If that is new business generation, customer service portals are then not an after-thought, but are limited to perhaps one prominent button, often in the upper right of the site. Subscription renewals, purchase histories and the like are treated similarly. Easy to find, but they get only a small fraction of home page real estate.