Implementation issues

I am working with users who are adamant that they would not want to make use of ABAP and prefer no customizations when implementing the Business Contents?

What would you make of this if you were working with these users?

Would you tell them that avoiding ABAP and customizations would be to avoid reporting accurate data?

What are some of the options that can be implemented without the use of ABAP and/or customizations(tweaking the business contents)?