You are absolutely correct. I've noticed some sets missing from the Browse by Brand lists. Also, this site is very inconsistent in the set naming. Some sets have the company and product names, while others produced by the same companies only have the product name. Irregardless of what is printed on the face of the card (Fleer Ultra, Topps Stadium Club). Then some add the company name when it is not printed on the face of the card but only in small print in the copyright line (Panini Elite).
My stance is all sets should have the company and product names. And it's an absolute fallacy to say "everybody knows them as Ultra". In their 23 years of existence I never heard of them referred to as just "Ultra" until I joined this site.
Someday my cards may double in value and then be worth half of what I paid for them.