There are only ~5 flat-panel manufacturers worldwide: AU Optronics, Innolux, LG Display, Samsung Display, Sharp Display, and recently BOE Display. Apple has to use one of these, even for its bespoke, notched, curved iPhone/iPad displays.
This new 5K 2304-zone panel was developed by LG Display, and is not 'generic white-labelled slop' by any means. It is an extremely good panel in its own right, probably the bleeding edge of LCD technology today achieving top-notch responsiveness, contrast, and colour depth and accuracy.
That MSI monitor will probably retail for ~£800 as will the Asus and LG equivalents, which is not a trivial amount for a monitor. Apple just marked it up 3×, as they are prone to do for anything.
Back in the day (~15 years ago), when 4K monitors were unheard of and even Apple's high-end displays were still 1440p, you could get a bottom-dollar monitor using one of their panels (e.g. Yamakasi Catleap Q270) for about a third of the price. However, it came with no amenities, a single connector (dual-link DVI only), a questionably legal power cable, and no built-in scaling. The vendors, presumably to prevent refunds, even asked for your graphics card model before selling it to you, because it wouldn't work with low-end cards. Oh, and there were very few in the U.S., so you were typically getting them shipped straight from abroad, customs duties and all.
We've definitely come a long way.
After a few years, the "cheap ones" have usually caught up, if you're willing to do the research.
These days they still value software at $0 but the specs have become quite competitive and many times exceed what the rest of the market offers.
Whereas with their laptops and almost everything else you might as well wait if you can, next year's is gonna be better and/or cheaper.
MSI - 1400 nits, LG - 1250 nits, Apple - 2000 nits. That's peak brightness, standard brightness isn't even mentioned, except for Apple one. Is it just cooling or something more?
[1] https://www.ipsmonitor.com/news/msis-mpg-271kraw16-is-a-firs...