The difference between them is becoming less relevant but most of what you want from a distro are good defaults and stability. Some people don't want to have to make 100 changes every time they download a distro to tune it to one specific task, so you have distros like Nobara which is tuned for gaming and productivity, distros like Endeavor which are Arch-based but with a ton of things set up for you, distros like ZorinOS which are tuned specifically to be beginner-friendly and have helpful popups, etc.

I think it could be argued that most distros out there now are "just Debian/Arch but with [thing]" but I still think the distro choice is important to people who don't like messing with their system and want things to just work.