Tech Bros 'cry' ( ideally it should be called as 'rightfully demand') about work life balance because this industry can afford it.
Tech industry is not person dependent like say healthcare or transportation.
In healthcare only if there is a nurse or doctor can a patient be treated.
In transportation only if there is a crew and driver can the vehicle be run.
Tech industry is a newer concept and it calls for newer work norms.
A payment company doesn't need engineers in their office on Saturday and Sunday and yet we can continue using their service.
A social medi accompany doesn't need engineers in their office on Saturday and Sunday and yet we can continue using them.
In case there is any breakdown, companies do call folks even when they are on vacation. The ones on medical emergency are rightfully excused.
FYI, old industry like banking too has gone to 5 day work week.
There is absolutely no reason why tech Bros/Sis should be expected to work on Saturday and Sunday.
If you want growth, better hire more engineers. Period.