They aren't if they don't have any Discipline Points, which is the point.
The problem currently with the Monk as spec'd is that they are reliant on a resource to do most of the stuff that actually relates to their subclass. You want to use your powers? Well, you start with two points of Discipline. Good luck!
I don't think the overall concept or design of the Monk is bad, necessarily. The problem is that Wizards and their designers are just like weirdly conservative when it comes to handing out resources to people who aren't magic. Further, if you have anything cool, that's gotta be tied to your resources. At the least, this time around they made things cost a bit less for some subclasses, but it's still not good. If Wizards wants to fix the Monk and put it in a good place, they need to decouple some of the things each subclass does from Discipline Points. Making everything reliant on using that resource means that you'll lose what makes you unique because just about everything keys off it.
So the first thing I'd do is starting making a few of the initial Discipline Point things free to different extents. For example, Dash should just be a free Bonus Action for Monks. It is for Rogues, why not give it to the class that is supposed to be fast? After that, we have FoB, Disengage, and Dodge. Controversially, I'd say every subclass should have one of these just as a special bonus action for free. A class that is meant to be kind of tanky, like the Drunken Master? Free Dodge. Suddenly now they are hard to hit all the time because, hey, they always have their wobble on. Shadow Monks get Disengage free because their whole gimmick relies on being untethered. Open Fist... well, I think they should just get FoB free. Yes, that means they get a bunch of attack output... but if you don't make changes to the monk's HP and force them to use their Martial Arts die, I think it's an okay tradeoff. They can spend Discipline when they need to Dodge or Disengage, but Monks like the Open Hand are meant to get stuck in, and mechanically it allows them to distinguish a bit.
Let's add something further to distinguish each subclass. Giving them an action that they don't pay for is a good start, but we can mechanically distinguish them further. The recent conversation was on giving them a different Weapon Mastery for Martial Arts... why not have each subclass give them a different one to use if they so want to? Giving a style with clawing attacks Graze, a hard-hitting style Push, a grapple-style Topple, etc. It gives another interesting distinction point for each class to make them more unique.
Now that you have a Monk Subclass that will be distinct even if you are lacking DP, you can start looking at things to add to and to key off of. Overall, I'd say that it'd be better to use DP to refill or do more rather than just having a tax to do something. For example, with Deflect Missile, I would just let someone toss a missile back for free, especially since it's a Dex Save for the target and it's already costing you a Reaction. Instead, what I'd do is make it cost a DP to Deflect Missiles if you don't have a reaction to spend. Suddenly the monk can pick multiple things out of the air at cost, rather than having one chance a turn to spend a DP on the off-chance they manage to completely nullify a missile attack. You could do that with other things, too, like maybe modify the DM's Tipsy Sway so that it doesn't autohit, but you can spend DP to redirect multiple attacks like you are actually Jackie Chan. Similarly, I think Wholeness of Body would be fine in the playtest if it didn't also cost DP: it's already got a daily limit, just let it be.
This is pretty rough, but overall I think just making more things free for the Monk would go a long way to allowing one to actually engage with the class. You don't need to increase the DP too much (Everyone here says Wisdom, but I would say use your Proficiency Modifier so that it advances with time), and that way each class as more of a defined style.
