This whole thing comes down the the old "George Washington's hatchet" story

This is the hatchet George Washington cut down the cherry tree with.
It has a new head and the handle has been replaced a few times but it is the
same hatchet!

If you keep fixing an old outboard it will go forever.
In a purely anecdotal account, the powerhead and foot internals of my Mariner
75 went over 3000 hours without any attention but I did replace the stator,
tilt/trim was rebuilt, replaced all the solenoids at least once along with the
usual maintenance items (water pump, plugs, carb kits etc).