Is fixing a typo in the docs enough? What about bugs reports? These are useful tasks for a open source project.
You may get contribution-spam fixing inexistent errors, just to fulfill the clause.
If developer X is working in company Y and a year later X changes to company Z, who can use the software Y or Z? What happens if X dies? What happens if Y goes bankrupt and W buys all the assets?
You may get contribution-spam fixing inexistent errors, just to fulfill the clause.
If developer X is working in company Y and a year later X changes to company Z, who can use the software Y or Z? What happens if X dies? What happens if Y goes bankrupt and W buys all the assets?