Ever since SharePoint Portal Server 2001 was released at the start of the millennium, developers and businesses have tried all types of approaches to customize and bend SharePoint, one way or another.
SharePoint, after a default installation (which in itself is a discussion for a whole other book!), is referred to as an Out-of-Box (OOB) SharePoint. In its history of 15 years of releases for on-premises versions, and more than 5 years of updates with SharePoint Online, developers have always found ways to modify, change, or even remove built-in SharePoint functionality. This could be because of business requirements, usability reasons, or simply that a developer feels that he or she can implement a better implementation of a SharePoint feature.
This has resulted in numerous issues and headaches for both Microsoft, ISVs, Microsoft partner companies trying to make a living providing SharePoint-based solutions, businesses and their IT departments...