I don't understand this emerging view that it is unreasonable for a RPG to set out principles for players and GMs.
It's not a new thing. It can be found in quite early RPG rulebooks, like Gygax's AD&D books and Moldvay Basic. I believe it is also found in recent D&D rulebooks (eg the DMG). I've found some on DnD Beyond.
The following is from p 114 of the Apocalypse World rulebook:
• Be a fan of the players’ characters. “Make the characters’ lives not boring” does not mean “always worse.” Sometimes worse, sure, of course. Always? Definitely not.
The worst way there is to make a character’s life more interesting is to take away the things that made the character cool to begin with. The gunlugger’s guns, but also the gunlugger’s collection of ancient photographs — what makes the character match our expectations and also what makes the character rise above them. Don’t take those away.
The other worst way is to deny the character success when the character’s fought for it and won it. Always give the characters what they work for! No, the way to make a character’s success interesting is to make it consequential. When a character accomplishes something, have all of your NPCs respond. Reevaluate all those PC–NPC–PC triangles you’ve been creating. Whose needs change? Whose opinions change? Who was an enemy, but now is afraid; who was an enemy, but now sees better opportunities as an ally? Let the characters’ successes make waves outward, let them topple the already unstable situation. There are no status quos in Apocalypse World! Even life doesn’t always suck.
“Make as hard and direct a move as you like” means just that. As hard and direct as you like. It doesn’t mean “make the worst move you can think of.” Apocalypse World is already out to get the players’ characters. So are the game’s rules. If you, the MC, are out to get them too, they’re plain [in trouble].
This goes for highlighting stats, too. When you highlight a character’s stats, try to choose one that’ll show off who the character is. Switch up often — for certain don’t just choose the lowest stat and stick with it — and try to make sure that the character usually has at least one high stat highlighted.
As this indicates, the principle
be a fan of the players' characters interacts with the principle
make the players' characters' lives not boring. It helps guide
how to make those lives not boring.
I don't see how it is supposed to be objectionable.
I also note that it is not a principle that would have any work to do in, say, GMing a module like Tomb of Horrors. It's a principle that, together with
makes the players' characters' lives not boring, applies in the context of a particular RPG, that is a very long way away from ToH, in respect of intended play experience, particular techniques to be used, etc.