Diablo V will not scale monsters the way Diablo IV does

Diablo II gave each area a level range, so you could outgrow a region and feel it. Diablo III and IV scale monsters to you instead, which keeps fights challenging and flattens the moment a level-up or a great drop is supposed to make you feel unstoppable. Asked about it in a BlizzCon group interview with PC Gamer, game director Joe Shely sided with the feeling:

You've filled the experience bar, you get stronger, you should feel awesome now [...] And sometimes automatic scaling can get in the way of that feeling, which is so core to it, and that's why this is a really important question. And so, we're going to take a somewhat different approach to that in Diablo 5.

That is the whole commitment. Shely also said the team has not fully discussed level scaling yet, so what replaces Diablo IV's system has not been described. Reports that Diablo V will use fixed, zone-based monster levels like Diablo II are filling that gap themselves: it is a reasonable guess, and nobody at Blizzard has said it.

Planning over reflexes

A week later Shely put the direction in genre shorthand on his own X account, in a post PC Gamer reported on 29 September:

While Diablo 5 will continue to feature some DEX (moment-to-moment execution) mechanics, on balance the game will be an INT/STR game (planning and investment). We are designing to the core tenet of ARPGs that any challenge can be overcome with the right build.

Read with the scaling remark, it points one way: a game where what you built matters more than how you dodge, and where the world does not quietly level up to meet you. It fits what Blizzard has published about items - itemisation strongly influenced by Diablo II, and an experiment with stat requirements on gear.

That reading is ours. Shely described a direction, not a system.

Why these are developer statements

Both came from the game director, by name, on the record - so they are not rumours. Neither is in a Blizzard post, so neither is confirmed. They sit in Everything we know under progression and endgame, with the source attached.