Right.
I've only ever seen takeoff from elevation... dock, side of boat. Or with powered help (like waterskiing start and drop rope).
Older folks will be hampered from falls, swim to dock, get out, try again (tiring to say the least). Not to say younger folks will find that much easier... but fitness is assumed to be better.
The other issue is injuries can be high... falling on the foil can result in deep cuts or broken bones.