It used to be that way. Traditionally, seed pelargonium produced small flower beds which petals which shattered quickly. Today, however, some very good competitive seed cultivars are present which fully match those of the old cutting grown (orbit, elite, multibloom, maverick, etc). You are correct that cuttings of seed grown pelagonium produce identical plants to the seed grown plant.

I would not hesitate to grow seed grown pelagonium today. If you want heirloom pelargonium then you have to go to cutting grown pelargonium.