This is the most realistic answer here. SAP is legacy software. Any company that has been using SAP since the 1990s is still probably running parts of software that were written around that time - or even earlier (!)
Actually, this leads to the same types of problems that everyone is discussing here over 'customizing'... at the root it is a collision of ever larger growing global companies with ever-increasing complex process that must rely on older and older code (or customizing) bases, because stopping everything and doing a total overhaul just isn't feasible at such scale.
Every custom program or customized process brings rise to a future risk of headaches/breakages when the system is upgraded, a process is once again changed, or something should be added to the process.
I guess the best analogy I can think of as an ABAP developer, is that it sometimes feels like running on a treadmill that just keeps getting faster...
Someone commented above how IBM used to be the company that was infinitely trusted... and indeed, SAP itself as a company is certainly not at fault, but until the environment changes with SAP customers and all their custom code and processes... I guess only time will tell...
The main problem is not the actual software it is the people who implement it.
Sap as a company has no control over the implementors. The implementors don’t understand how the software is intended to work.
I can compare it to Samsung Android vs Google Android.