Before I start, I've never even tried on a Seek Outside pack or even seen one in the flesh. So take that for what it's worth.
In response as to why they aren't more popular, I frankly didn't even know their company existed until probably 2019, and didn't know they made packs until about a year ago. I knew them as a shelter company when I first heard of them, but I never even knew they had anything to do with the pack industry. They just aren't the name you hear thrown around on all the big review websites or Youtube channels or review videos.
As an example, Huntin' Fool did a video comparing like 7 big name hunting packs. It's actually a good video I feel, and one I've referenced a couple of times over the past couple years. They made no mention of Seek Outside (to be fair, they also didn't mention Kifaru), and I think this happens all the time. Pack comparisons on hunting websites compare the "big names" and oftentimes other solid companies are looked over.
Think about optics. When we mention the "Alpha Glass," the names that come to mind are Swaro, Leica, and Zeiss. But take a poll on Rokslide and I bet most guys would agree there are other brands that hang right there close, like Meopta and Kowa. But because they're not the "big names" in the hunting space specifically, they don't have any recognition outside niche spaces like Rokslide. And yes, whether we want to admit it or not, Rokslide is a niche market. Take a poll of the general hunting market and most guys don't even know what Meopta or Kowa are.
I feel Seek suffers from the same type of thing. For guys who are "in the know" it's understood they make a solid product. But get outside of places like Rokslide, and the brand name recognition in the hunting industry falls off a cliff. But Exo, Stone Glacier, Kifaru, Mystery Ranch, ETC. have all the brand recognition in the industry because of... wait for it... marketing. Like it or not, those companies have successfully marketed their way into people's minds, and Seek Outside hasn't done that. And because of the way we as humans consume media and gain knowledge nowadays, electronic marketing is what sells your product.
EDIT TO ADD BELOW:
We buy everything online in modern times, so it does no good to get your product in a big box store. Much like how Jack O'Connor sold a metric boatload of Winchester Model 70's and 270 Winchester chambered rifles by writing about it in Outdoor Life and other hunting magazines, places like Rokslide are the 2023 version of those publications from the 50's, 60's, 70's, 80's, and even into the 90's and 2000's. If your product is only making it into one or two of those modern day "publications" (Seek Outside), vs. those same publications plus 1000 more such as podcasts and Youtube reviews and TV shows (Mystery Ranch and Stone Glacier, for example), you're going to have a narrower reach than your competitors.
Whether you love or hate modern marketing, it's no different than what guys like Jack O'Conner, Elmer Keith, Warren Page, or Townsend Whelen were doing +/- 50 years ago. The medium through which we receive that marketing may have changed, but the basic means and methods are the same. Seek Outside is struggling with obscurity the same way the WSSM cartridges did or the 6.8 Western or the 6.5 Rem Mag did, which is through unsuccessful marketing RELATIVE TO its competitors. Doesn't make their product any less relevant or any less awesome, it just means they're disadvantaged in the marketplace because of it.