Arrow functions are used everywhere because:
Safety of scope: When the arrow function is used everywhere, it brings consistency of scope because the same thisObject is used everywhere. If by any chance, a standard function is used alongside the arrow function, there are chances of the scope getting mixed up.
Compactness: As compared to the standard function, the arrow function is compact as it does away with the need for keywords, curly braces, parenthesis, etc. in certain cases. It is, therefore, easier to read and write.
Clarity: When the arrow function is used everywhere, there is a certain consistency of scope. Thus, whenever a standard function is mixed with it, it stands out distinctly. The developer can therefore look for the next higher function to locate the thisObject.