Because more often then not, these machines are too expensive for them as much as I love Sebos, Central Vacuums, and other high-end machines, it's important to realize that they're just that: high end. Not everyone has $600+ to burn on a vacuum cleaner.
There's also the whole thing of people simply being manipulated by marketing into buying such bad machines. In other words, a product doesn't need to be good, it just has to be advertised right. And because most people are not vacuum experts, it's a lot harder for people to distinguish the crap from the cake. A prime example of this is with Sharks and Dysons. They can make the I'll-founded claim that "most vacuums lose almost all of their suction after a while!" Then pitch you on a vacuum that is more maintenance, hassle, and worse performing, but you'll still have faith in it because you were told that it doesn't suffer from suction loss. Even I was one with these people long ago. I watched the infomercials for the Shark Rotator, Powered Lift-Aways, and other machines, and were immediately sold on. Of course now I know those machines are mediocre at best, and I wouldn't recommend them over something like a bagged machine or some sorts. I think today's equivalent would be Tiktok influencers getting paid to advertise machines from both well known brands and no-name brands from Amazon and Walmart.
I'd say that all of this really began with Dyson, though another company to blame would be Rexair and their machines, but that's a different can of worms. They sold people on the idea that suction loss was a catastrophic issue plauging 99% of vacuums on the market, and that only dysons were immune to this because they had cyclones. Other vacuum manufacturers saw this, and then naturally had to compete, and so this big lie of suction-loss and cyclones has shaped the vacuum industry to what it is today. I've tried real hard to convince some people that bagless is not the way to go, but they've been fed these lies for so long that nothing will shake them.
In short, It's not the consumer's fault.