Alt+Left requires two fingers, but not two hands. You're aware of the alt to the right of the space bar, yes?

In France at least we have an Alt-Gr key (roughly equivalent to holding Ctrl+Alt) on the right of the spacebar instead of an Alt key. And unfortunately Alt-Gr+Left does nothing. So we have to use two hands to press Alt+Left, that's why I personally prefer using Backaspace

Not on many European layouts.

In many keyboard layouts, this key is not an Alt modifier. It is, rather, level 3 shift (in ISO 9995 terminology) - a.k.a. "Option", a.k.a. "Alt Gr".

Not all keyboards are the same. Think Laptops, international keyboard layouts etc.

On American keyboards.

It's not the keyboards. It's the keyboard layouts that are configured in software. And not all "American" keyboard layouts make that key an Alt modifier. The Microsoft Windows "United States International" keyboard layout makes it level 3 shift, for example.

And if one includes North America and South America in "American" the same goes for the Canadian Multilingual and the Brazilian Portuguese layouts. (-:

Thanks for pointing this out. Should be fixed soon: crbug.com/613201.

The grandparent suggested - Alt+Backspace