PC version is the same as the PS4 version aFAIK. Has Paragon levels, but 1% more speed or critical chance isn't levelling up in the same way as getting skills. As I say, D3 is about the numbers, and working towards getting ever bigger numbers. Games like CON were about slowly levelling and the thrill of getting a new skill.
We're on the hardest mode available for beginners whatever it's called, all playing fresh level 1 characters, not using any inventory items or stored cash to buy better gear. There's no way to make it harder short of not equipping gear.
It's just not made that way. Which is understandable - the game has sold squillions and people play it to death and beyond so it's a formula that works! I've sunk hundreds of hours into it myself. It's just...it's like a sort of junk-food of gaming IMO. It'd be nice to have a game of this ilk that was...grown up. That challenged its players rather than being about just crushing through countless mobs and churning through thousands of irrelevant pickups for the 0.01% that actually matter. All IMHO.