SoundFont® synths were never good. When Creative added this feature to their sound cards, they were trying to provide a cheaper alternative to dedicated hardware synths, but it did not match the quality (though it was still a step up from FM). And in the modern era, this obsolete format has somehow become more popular, now via software reimplementations, because of the catchy name or something?

I also want to point to Nuked SC-55, but that is also not based on SoundFont®.