That's true, but you are only seeing the mine @arr case, where it was until recently impossible to change the underlying \@arr reference.

If you want to also cover the mine $arr=[] case, @arr := @$arr has to become magically adjusted or an alias or ...

Update

Till now most were only talking about the implementation, and that they reject the notion that equal symbols are bad or mostly useless.

Nobody commented on the idea to simplify the syntax with implicit refs.

FWIW: this could also be achieved by introducing another sigil like ¢ for automatic refs, hence avoiding a keyword mine

But I seriously doubt this is doable and worth the trouble.