That was asked in a private discussion, but let me share my opinion publicly for free so at least y'all can learn and benefit from it.
Real cost of relying on volunteers to do open source:
- can't stick on schedule. It's whenever they have free time. maybe never.
- can't pick and choose the level of expertise and experience of the volunteer. you might just get newbies/AI who introduce more bugs/tech debt for you to fix
- no continued maintenance. they made one PR and then leave.