Do you consider games like Diablo + Hellfire to be real RPG games?
Or are they fake RPG's cause there is only one-way conversation (you don't choose what your character says) and cause the focus is on combat
Diablo is a different kind of RPG. That's an action-based RPG, often referred to as ARPG's. They are their own thing, more or less, as part of the ARPG sub-genre of RPG's.
Basically - you pick a certain class/character/hero - and you constant defeat enemies; get new unique loot; mod unique loot; level-up your character and their stats & skills. ARPG's and Diablo-likes do this in the extreme sense of it - as they do this on a level of their own, where this is the focus and main goal and gameplay loop. This looting & leveling stuff is the primary part of the game - often the story and decision-making are secondary...or non-existent...or close to non-existent.
Even D2, is basically a dungeon-crawler here - it's just you ain't jumping down and down into each dungeon like say Diablo 1. You're now also out in this game's actual game-world in the open, above ground, and in towns. It still acts like a dungeon-crawler w/ its constant combat; constant running around and grinding for levels & loot; and whatnot.
Tons of ARPG's like Diablo series - Grim Dawn; Sacred 1+2; Dungeon Siege series; Space Siege; Silverfall; Van Helsing ARPG; Titan Quest; etc etc etc.
Also, you have games like Hellgate: London and Borderlands series - which heavily mix a lot of shooter elements and ARPG elements together.