When designing product stuff, it’s important for elements that behave the same to look the same, or at least similar. Conversely, it’s just as important for unlike elements to appear unlike and be inconsistent. Following conventions like this prevents unnecessary confusion.
Some conventions are global. For example, most people are used to in-line links being underlined. It is rarely a good idea to break these conventions unless you have a solid reason. Other conventions are local to industries. Words, purposes, how things look and feel.
The whole point is to give people the freedom to do the things they want to do. Think of a ‘back’ button. This is a good global convention. People should always be able to “go back” on a mistake without too much hassle.
Improve on conventions that force people into unplanned interactions, confusing pathways, and surprising outcomes. A solid reason not to follow a convention is when it threatens someone’s freedom.