I love how you parsed my statement into two separate items as if they weren't part of the same thought. I see you are not arguing in good faith.
Before accusing anyone of dishonesty, you should consider the meaning of the word "especially" and how it might reasonably be interpreted by others reading your argument. "Cake is delicious, especially when it's chocolate" != "Cake is delicious when it's chocolate".
What's the point of this tautology?
You assumed that I was arguing against monks and druids having this feature, and you have also repeatedly cited monks and druids as reason for rangers having this feature. I was succinctly rebutting both points. That I was simply stating the obvious (though not an actual tautology) only underscores the shakiness of your assumptions.
Because 5e has an established precedent for handling characters attacking without weapons still being able to bypass DR/magical. Making it a spell instead just adds more clutter. And makes it a spell tax. It's an inelegant solution when an elegant solution already exists.
That's like saying
fireball is inelegant, cluttery, and a spell tax, and it'd be more elegant if sorcerers just got the ability to throw fire as a class feature. Doing the magic thing within the established mechanical framework for doing magic things is more elegant than doing the magic thing through an ad hoc entry in the class feature list.
And what Hong Kong movies pray tell have "monks" or "martial artists" fighting literal ghosts?
You kidding me? You can start with any of the gazillion adaptations of
Journey to the West, go into movies like
A Chinese Ghost Story where it's right in the name, take a detour through the entire subgenre of jiangshi films (admittedly more zombies than ghosts, but still requiring sacred magic to deal with), and even cross the Pacific for Hollywood's take with
Big Trouble in Little China. So yeah, monks vs. restless spirits is a big-time trope.
On the other hand, when ranger-type characters encounter restless spirits in
Lord of the Rings or
Game of Thrones, both of them have to acquire and use magic weapons to deal with the problem. Now, admittedly, Aragorn doesn't have an animal companion -- but Jon Snow does, and it's still the weapon rather than the wolf that's effective against the White Walkers.
Also, most monsters that have DR/magical in the first place don't have weapons to disarm, or even might be too big to disarm, trip or grapple. Not nearly as reliable as a spellcaster's good ol' Forcecage.
So you adapt the tactics to fit the particular challenge.
That's the point. Forcecage has size limits too, for what it's worth: anything that can fit into the solid-sided version can also be tripped or grappled by a Medium creature, and the barred version of course comes with its own drawbacks. It's a spell that can be very strong or not so strong, depending on the circumstances, which is what makes it interesting. If it were strong unconditionally, it would be poor game design and a spell tax.
But you're not giving EVERYONE that key. You're giving one full class and one subclass that key right now, and maybe another one, too. That's not "everyone." Hyperbole makes your argument null and void.
Your argument is based on the assumption that everyone gets the key, if not always through a class feature. You call it
"the same thing that literally every other character is able to do 100% passively in some form or fashion".
What makes an interesting game? What makes interesting class features?
Players making meaningful decisions.
Why can't a means to passively overcome DR/magical be interesting?
The word "passively" is a big warning sign right there.
What if the Beast Ranger *gasp* needs that feature to actually BE interesting, or at least be played according to its inherently interesting concept?
Then the mechanic that creates this necessity, nonmagical resistance, is bad for the game precisely because it creates this necessity and adds nothing positive to gameplay. You complain about spell tax, but what you're describing here is a
feature tax, and you seem for some reason to be enthusiastically in favor of the situation. Fortunately for the game, nonmagical resistance does
not create this necessity, and the beastmaster ranger, moon druid and monk would all still be interesting if they didn't get passive ways to overcome it. The monk might lose some conceptual capital because it can't realize the aforementioned monks vs. spirits trope as well as it could. But the druid would be fine, and the ranger is fine. Just like sorcerers are fine even though spell resistance is a thing. And barbarians are fine even though ranged attacks are a thing.