Travel system or separate car seat and stroller

I am looking at strollers and car seats. The stroller I want comes separately and as a travel system with a car seat. The car seat is only good for infants though. Wouldn’t it make more sense to buy the stroller separate and buy a convertible car seat that is good from birth up to 65lbs?? I don’t see the point of an infant only car seat or am I missing something?