A customer portal is worth building when the same requests arrive every week: order status, documents, pricing, parts, booking history, member details.
Email does that work until volume makes it slow and inconsistent. A portal gives a signed-in space for the information you are already willing to share, with permissions so people only see what they should.
It is the wrong first project if customers barely return, or if the underlying data still lives in an untrusted spreadsheet. Fix the source, then expose it.
Portals sit naturally beside e-commerce, quoting and internal systems. Brendon’s MyBrendon work is an example of a customer layer designed around products and services the public website cannot hold on its own.
If you are answering the same questions by hand, a portal is often the cleanest business system to start with — and it links forward to websites, accounts and integrations as the rest of the operation catches up.