Truly, it only takes a few seconds to realize that The Walking Dead's Whisperers are a fundamentally different kind of threat than the many that have come before them, and those that will come after. From their stealthy transport to their skin-crafting to their emotional detachment, the Whisperers don't behave or react like traditional people, and thus any efforts to take them down will need to be equally different.
The Walking Dead's showrunner Angela Kang recently talked about how the war against the Whisperers in Season 10 will be quite different from the battles that these characters have faced in the past, and she details why the approach is different. In her words:
Baked into the Whisperer story is this idea of the border, the spiked border, and just thinking historically about all the kinds of border conflicts that people have gotten into, that we get into right now in our own country. But even in wars, what does it mean to own a piece of territory? In some ways, a border is this completely arbitrary designation that two sides have to agree on or not. And that just led to a lot of ideas about the types of stories we could tell with people who maybe feel like they're on the wrong side of the conflict, or people who might want to escape from where they're at, or people who may be trying to spread paranoia and fear. It led us down different paths than we might have in past with stories of battling each other, that we found really fun to play with creatively, and that I hope pay off for the audience when they watch the show. Because it has certainly been really interesting for us to explore [war] in this kind of framework, as opposed to just, what are the coolest battles we can have?
Previously, a group's borders were marked by more direct manners, such as the wall around Alexandria, or the walker-adorned fence around the Sanctuary. But because the Whisperers are a wandering group that doesn't have a central establishment to go back to, their borders are definitely more arbitrary and abstract. That's precisely where the power lies, though, because if the Whisperers can convince Carol, Daryl and the rest to stay behind a completely invisible border, it's indicative of the kind of power Alpha's crew has over the good guys.
For another point, the All Out War against the Saviors was a bullet-heavy conflict that was seemingly tied to whoever could create the biggest body count, with Rick & Co. choosing first-degree murder ambushes as a choice strategy. However, the Whisperers aren't the kind of group to go after with guns blazing, even if ammunition shortages weren't an issue.
Angela Kang talked about that point a little more while taking part in THR's podcast Series Regular. Here's how she put it:
I think one of the things that we kind of thought about early on, and that I'd been thinking about, is that we've done a series of wars on the show. We did ‘All-Out War’ with the Saviors, and that was really an all-out war. There were a lot of gun battles back and forth. That was the nature of the conflict with the Saviors, and at that period of time. But because I'd kind of made this decision to jump a lot of time within the show, that changes what the nature of war is going to be in the timeline that we're in. So we started thinking about that.
Truly, it's strange to think of how many years have passed since Rick brought Negan and the Saviors down with a throat slice (that got patched up for SOME reason). The characters have had a lot longer than viewers to sit back and reflect on the positives and the negatives behind how to approach situations like this. It can be assumed that at some point, Michonne and the rest had a conversation where it was made clear that any future conflicts with outsiders would need to be handled in a way that wasn't just an exodus of bullets.
Of course, I doubt Michonne or anyone else could have foreseen the psychologically terrifying Alpha arriving to cause confusion-laced chaos within the communities. The Whisperers create a mystery-infused threat that can't be strategized against like other villainous groups allowed for. If a pack of 50 walkers is headed in a general direction, that pack could indeed have 50 walkers in it, or it might just be 5 walkers and 45 Whisperers. Since using guns brings more walkers, it's easier to take them out one by one, which is a lot harder to do when you're not sure what you're up against, or who they'll be willing to victimize to get their way.
SPOILERS for the Season 10 premiere: The Season 10 opener featured the protagonist group crossing the Whisperers border in order to stop a raging fire influenced by satellite wreckage crashing down, and the very end of the episode saw Alpha catching Carol in the no-trespassing zone, which likely means some danger is coming Carol's way in the near future, though I'm sure she's not alone. (Hopefully Maggie's arrival in Season 11 is one free from Alpha's threats.)
With Thora Birch's new character Gamma coming, it's expected for the Whisperers War to take place across most of Season 10, assuming it doesn't bleed over into the recently announced Season 11. So be sure to watch it all going down on AMC every Sunday night at 9:00 p.m. ET.