Boats hauled out for whatever reason safely sit on their keel, sometimes for years without damage, so the static weight is irrelevent. When the keel is submerged in mud, the dynamic stresses from a moving water column or waves can induce stresses for which the hull/keel joint is not designed. If, by chance it is an Ericson 27 or something similar with an integral keel, it's much less of a issue. It is conceivable that the keel joint could suffer over time from such stresses but it's unlikely if the marina is sheltered.
Regarding abrasion, it obviously depends on the bottom composition but the bright side is the barnacles won't be happy...