Jeremy Mortimer wrote
The OP was using light randonnée boots,
which are very soft.

Yes, stiffer boots do address part of the problem of breakable crust. I'm
just saying that there are other problems which great skiers address by
other means which include strong back-extension muscles.

light randonnée boots = very soft.

No -- "very soft" is old leather 3-pin touring boots with no buckles, like
my Asolo Snowfields.

I think from a "backcountry" perspective, any randonnee or "Alpine
Touring" boot is in the category of "stiff", and some are stiffer.

Ken