It’s the same in C/C++ and Java. And removing support is a breaking change for existing code, though I yet need to run into someone who uses octal.
Removing it surely takes the fun out of coaching juniors, where some like to align values in code, like:
var a = 200;
var b = 080; // decimal 80 in JavaScript, as 8 is out of range for octal
var c = 070; // decimal 56
That’ll teach them. 