My best explanation of why you don't want hermaphroditic plants for your smoke.
They have the potential of seeding themselves and others. This is bad not only because your smoke will have seeds but much more importantly when a bud becomes pollinated it stops the process of producing THC and begins a new process of creating a seed. Thus makes the smoke less potent.
merriam-webster:
sin·se·mil·la
noun
American Spanish, from sin without + semilla seed
Date:1975
: highly potent marijuana from female plants that are specially tended and kept seedless by preventing pollination in order to induce a high resin content ; also : a female hemp plant grown to produce sinsemilla
I will add - this is why we do things like select choice plants and not just use dirt bag seeds - for the best results