Because Ars Magica is a really good game.

Thank-you - I was searching for "Ars Magica" here in the comments - as it is the only fantasy RPG that I have ever seen come close to having the "feel" of actual "medieval" times, except - of course ... for the magic... (It is also the absolute best magic system out there!)

Not a tabletop but the Kingdom Come Deliverance video game has completely changed my previous very similar opinion. It's one of the best action RPGs of all time and it's historically accurate and realistic: https://store.steampowered.com/app/379430/Kingdom_Come_Deliv...

Fair enough but that's not fantasy.

Realism is a sliding scale. Some people prefer to count their arrows after every combat, some people prefer to go into a dungeon without even checking whether they have a backpack, much less whether it has any rations in it.

Having tried it myself: because it can be really fun! More magic, more dragons, more princesses does not inherently make a story better.

Why should you hate the idea?

I mean, I don't think the author is claiming that you should; they're just saying that it's not medieval.