SAP, at its core, is an ERP system. Those, in turn, run around MRP (Material Requirements Planning), all in xompliant and auditable manner (if used properly, that is). There is a reason why ERP systems rule the manufacturing world, and SAP rules ERP systems. All the chatter about CTOs going golfing with some SAP sales rep not withstanding, SAP is a very solid system and used by very sophisticated folks (ideally, if not, well, you cannot blame Red Bulls latest Formula 1 car if
I crash it in turn one).
So, if you are a manufacturing business, MRP is a must and SAP an expensive but solid choice. If you are not, and thus don't need MRP and ERP, well, you wouldn't use a semi truck for your weekly groccery shopping neither.
People who only look at the UI, and then not even the UI of the core funtionality of an ERP system, and then dump on, e.g. SAP (all ERPs are the dame but different in that regard), just show that they have zero clue what those ERPs are supposed to do and how they are supposed to be used.