Shared accounts can appear efficient because one username and password gives several people access. The operational cost appears later: nobody can easily prove who used the account, password changes affect everyone, and former users may retain access.
Accountability
Individual accounts associate actions with a person or workload. Shared credentials obscure that relationship and make incident investigation more difficult.
Offboarding
With individual identities, access can be disabled for one person. With a shared account, the password normally needs to be changed and redistributed to every remaining user.
MFA challenges
Multi-factor authentication works best when the factor belongs to the same individual as the account. Shared accounts often encourage shared phone numbers, shared authenticators, or exceptions that weaken the control.
Password distribution
A shared password must be delivered to every authorized user and may be copied into many places. Each copy becomes another exposure point.
When shared accounts cannot be avoided
Some appliances and legacy applications support only one administrative identity. Store the credential in a managed vault, restrict who can retrieve it, rotate it after staffing changes, and record administrative activity where the system allows.
Prefer named access for new systems
When selecting new services, treat individual identity, role-based access, MFA, and audit logging as operational requirements rather than optional features.