1 horse many nominations

Does a trainer not effect the final field by nominating a horse in multiple races at the same meeting. Hoping for a better draw or something they are effecting the quality of a field as other horses that may have run are withdrawn due to high draw or not wanting to race against certain runner.

Example

and i am sure there are more but i spotted this one.

Arboreal nominated for 5 different races at the next 2 Cape meetings.

Surely there should be a limit on number of concurrent nominations for one horse.

WOULD it not improve the quality of horse taking part as less good horses would come out due to high barrier draws for one.