There are no stupid questionsDitto +10000000000000000000000
Most folks in general do not understand the relationship of sensor size, pixel density, and pixel size. For many, the picture they take on their phone looks great on that little 4 inch screen. Put it on an 8 by 10 print and it doesn't so much anymore.
Most folks who own good DSLRs are shooting crop sensors (APS-C). Those sensors are already 500 times bigger than an iPhone. Full frame is simply twice as big as that. Mr. Haines nailed it for you.
But again there are never stupid questions when you're trying to learn!