Because a shared folder has no owner, no clock and no record. Everyone assumes somebody else replied, and the enquiry that has been open four days is discovered when the sender chases.
A shared inbox is a team address — sales@, renewals@ — whose messages are matched to accounts, assigned to people, and recorded as activity rather than sitting in a mail folder.
Each message is assigned, has a state and an age, and matches to an existing contact where one exists. Handled mail becomes activity on the account, so the history is where the relationship is.
An enquiry to sales@ from an existing Bexley Group contact was matched to their open renewal and assigned to its owner within the hour, instead of being answered as though they were a stranger.
It is not a helpdesk. There are no SLAs, queues or CSAT here — when a message is support, convert it to a Desk ticket, which keeps the history and adds the machinery.
The activity timeline records it, contact records match it, routing rules can assign it, and Desk handles anything that turns out to be a support issue rather than a sales one.
As many as you run. Each has its own assignment and routing rules.
Convert it to a Desk ticket. The thread and the account link go with it.
It creates a lead rather than a contact, so an unknown sender does not silently become a customer.
Fourteen days, every module, no card. Or half an hour with someone who will run it on your own records and tell you where it does not help.