How are any of the things ''forced'' in HR any more than they are in DX. They work exactly the same way.
Yeah, they work "the exact same way", as in, you write down a description on how Deus Ex' levels work, and then you interpret it in the most literal way possible so that it ticks the checkbox. Deus Ex allows you to do things either stealthy or violently, which I guess translates into "combat path" and "stealth path", even though in Deus Ex the distinction between the two is rarely that clear.
What is the "stealth path" on Liberty Island? Does it mean climbing up the boxes at the back of the statue? Or perhaps taking out the bot in front with an EMP grenade, bypassing most of the human defences this way? Who knows! Both "paths" are suitable for either an all-out assault or sneaking in, depending on what kind of hardware you're carrying and what your skillset is. Inside the statue lobby you'll find a vent (the only one on the entire huge level, unless I'm terribly mistaken), which I guess could be seen as a "stealth path", but you'll still have to figure some way to deal with the enemies, and the path isn't really any stealthier than just disabling the laser trap and avoiding the vent altogether.
What about Vandenberg? Is it considered stealthy if you start to take enemies out one by one with a silenced sniper rifle up from the rooftop? What about the bots? Do you eliminate them from a long distance away by using the spy drone, or maybe descend down to the yard, sneak past the patrolling enemies and set up EMP grenades in the proper spots? I mean, both approaches are definitely stealthy, but they're also very different, and instead of EMP weapons you could choose to use LAMs or rockets instead, which I guess would turn it into a non-stealthy approach, even though it's technically still the exact same "path". And if none of this suits you, you could reprogram the bots to attack each other, which would lead to all hell breaking loose but would allow you to remain completely undetected yourself, so I guess the stealthiness of that approach is debatable as well.
In Hell's Kitchen you could approach the NSF warehouse through the ground (a route that is filled with traps) or the rooftops (filled with NSF troops), but neither path is necessarily more violent than the other — a good hacker or electronics specialist might feel more at home with the traps, but sneaking through the rooftops is viable as well. This is probably the most obvious instance where the game gives you two different paths, but even then the distinction isn't really about combat versus stealth, it's about humans versus electronic defences, which adds another layer to the different approaches that the game offers.
Sure, Deus Ex does have areas where vents clearly provide the stealthy option. The Battery Park train station, the Hong Kong helicopter hangar, the VersaLife facility and the MJ-12 prison come to mind instantly. Even in those cases the game often forces you to leave your comfort zone and look for alternative ways to remain undetected, like finding a computer that allows you to disable the security system or turn it against your enemies, or figuring out a way to reliably take down a group of enemies that aren't just waiting for you to take them down one by one, but I guess you could make an argument that it isn't all that different from Human Revolution's approach. Where the game truly shines are the large outdoor areas, though, where the concept of different "paths" is pretty flawed to begin with, since you can approach the levels in so many different ways and pretty much create paths of your own. Human Revolution is severely lacking in this department, and the closest it gets is probably the mission in Singapore, which has an outdoor area with several buildings that are connected to each other in various ways, so that the line between "combat path" and "stealth path" gets blurred, and the game allows you to be a bit creative for once. That's something I'd definitely like to see more of in the upcoming game. The vast majority of Human Revolution's levels feel like straight corridors where they added some vents, side rooms, movable boxes, keypads etc. to create a number of different approaches, but it doesn't allow you to have as much room for planning and creativity as most of Deus Ex' levels do.