IKEA doesn't actually make any modular wall shelves like that anymore, after discontinuing the SVALNÄS. For a wall mounted shelf on a budget you could go for the Elfa system or the Fasttrack one.
It was a genuine question about what makes these any better (...or not). Like do they have some amazing non-obvious feature? Something that no other shelf has? Something that IKEA shelves fail to do?
Of course it could be a performative thing (as I was suggesting) in the same way that someone pays $150 for a t-shirt because it has a logo on it and they want people to know. There is a sucker born every minute as they say.
That’s fine if you buy exactly what you want and need and know your needs will never change, but if you later want to expand, you’re out of luck. At best, you might get lucky and find parts of Facebook Marketplace or Gumtree, but you’re usually just stuck. (I’d kill for some more 200cm wall rails but I doubt I’ll ever find any.)
The 606 Vitsoe system is heinously overpriced but has the advantage of having been around for 50+ years and is so established you’ll likely always be able to buy more parts if you want to expand it.