Just been reading up on it and it does seem the game has drifted away from a good experience for new players.
I just fancied a solo campaign kinda thing. I don't really want to take on board all these different play modes.
Blizzard perhaps should've considered first timers buying it on the Switch release.
The thing that's annoying to me is the extra difficulty levels give mobs more hps more than raise their damage, so on harder settings it just feels like a slog.
I don't want to play for hours to unlock or understand the other modes.
Thanks for your reply though but I might move on...
If you want to keep the speed but up the damage the monsters deal then I'm afraid you'll be disappointed. As you can tell from the list of difficulties that @mmovin posted, the health of monsters scale faster than their damage output. Diablo III is about speed and efficiency, you want to gain as much as possible as fast as possible. I usually start on "hard" then lower to "normal" when things start to die to slow, not because I die but because it's just way to slow. Eventually I get an item that gives a skill a massive damage increase, then I can go up in difficulty again, repeat.
At max level I like to just aggro as much as possible and as many elits/champions as possible (them blue/yellow named monsters). It can become really chaotic and fun, dashing around dealing damage and avoiding things.