I hate how "hack" is used for any kind of breach. This is 100% credential re-use or a shit password:

The attackers appear to be using leaked credentials or brute-forcing to attempt to take control of a large number of LinkedIn accounts.

And

For accounts that are appropriately protected by strong passwords and/or two-factor authentication, the multiple takeover attempts resulted in a temporary account lock imposed by the platform as a protection measure.

That's not to say LinkedIn isn't a steaming pile of garbage, but to say this is a "hack" is disingenuous.