Using CONCATENATE vs & with text strings

Appsheet provides CONCATENATE to merge strings. Such as in this post by @Lynn:

Question: why use the more complicated CONCATENATE, while the & works just as well (like in JavaScript)? Is & not really supported?

I think & came later as a shortcut. Note that Excel (upon which AppSheet’s expression syntax and functions are (sometimes loosely) based) and other spreedsheets have both CONCATENATE() and &.