SSH key based authentication is the default method that any Linux admin would choose for granting ssh access to Linux servers or Linux cloud instances. SSH key based authentication is the preferred method since its far more secure and more popular than password based authentication. The two commonly used keys for authentication are RSA and DSA and RSA Keys are preferred since DSA is known to be vulnerable.
Its good to have SSH Key based authentication but imagine the amount of management that has to be done if you have 100 employees and have 1000 Linux instances and how do you grant access to the employees to the thousand Linux servers or Linux cloud instances? How do you add the ssh keys to grant access ? How do you remove the ssh keys when the employee leaves the company? How do you rotate the keys?
You would have to manually add the keys to all the Linux servers and cloud instances to grant access and when an employee leaves, you would have to ensure that the employees public keys are removed from all your servers failing which it becomes a serious security issue.