IMHO this is poorly researched article. Couple of things mentioned as disadvantages of serverless are already solved in the market.
1. You can use serverless framework or other framework available in market instead of doing everything in GUI
2. Its easy in most cases to invoke locally by using serverless invoke local --function functionName.You don’t have to redeploy.
3. For monitoring you can create different Dashboards on AWS. Also a great solution is integration to Datadog or you can create alerts for specific number of errors or number of invocations and forward it to specific email address.