Bought my iMac 7 years ago with 8GB as the default memory option and a 1TB fusion drive. And here we are, nearly a decade later. Still 8 GB in the newest models. Still 1 TB fusion drives. GPUs haven't even seemed to take a jump over last year's models.
Plenty of folks use an iMac as the primary family machine - email, homework, some Netflix, kids' basic games. 8 GB is entirely sufficient for that. Hell, four probably is. If you're doing Photoshop plus a half dozen VMs, you buy it with more RAM.
[1] https://www.apple.com/shop/buy-mac/imac?product=MRR12LL/A&st...