Sometimes you have constraints and are limited to crontabs. For example when you are using autoscaling on AWS EC2 (https://docs.aws.amazon.com/autoscaling/ec2/userguide/ec2-au...).

I know, with eventbridge and lambdas this problem could be alleviated a bit, since eventbridge uses cron syntax but with some added bells and whistles ( https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-...) which would make the expression for the first monday of each month much easier to write.