Taking into account the much lower build quality, lack of webcam, mic and decent speakers I am not sure this is such a great deal compared to the Studio display.
Depends on what you're looking for. Apple packages a number of functions into one compact product and if you value each of those things, it's not a bad deal. A list of factors I've seen held out for the ASD before, with some counter-arguments:
1.) Superior build quality - but does it matter? A 27" display sits on a desk or table in a protected indoor environment and is seldom moved, for many seldom touched, and if the competition's build quality is adequate, how much 'value add' is there with a sturdy aluminum body?
2.) Aesthetic appeal - decent, but many people don't find mainstream competition ugly, most of the time we only see the screen, bezels and maybe stand base, so... Maybe the back of your monitor sure is pretty, but...?
3.) Webcam - reports vary from pretty good to rather bad. Some people like Center Stage and some don't care. Many people rarely use a webcam, and some who do would prefer a superior 3rd party option or use their iPhone in Continuity Mode. As for lack of mic in the Viewsonic (based on your post), 3rd party webcams can offer that function.
4.) Spatial audio sound system - the ASD gets consistently high marks for sound
by the standards of display speakers (which harkens to an old Sherlock Holmes' appraisal of a couple of Scotland Yard inspectors being 'the best of a bad lot'). From what I've been told, not hard to beat with external speakers, and many people already have external speakers or can get them fairly cheaply.
5.) Glossy display - seems most displays today are matte, which suggests a lot of people prefer matte, but yes, for maximum detail/sharpness and 'pop,' glossy is nice. And it's expensive to get the ASD matte option if you want it.
6.) Nicely integrated with your Mac (e.g.: Apple keyboard brightness controls work). On the other hand, lacks HDMI and DisplayPort, use with something other than a Mac can require some workarounds (e.g.: Thunderbolt input), and while it's technically a Thunderbolt 3 display with some ports, it doesn't have Thunderbolt output.
7.) Excellent color accuracy right out of the box. Sounds good, but some competitors in recent times get praise, too.
And let's not forget it's a ridiculously expensive up-charge to get height adjustability, if you want VESA mount capability you need to forego the stand (or vice versa) IIRC, and it doesn't do portrait mode, right? And if you don't pay for Apple Care+, you get a warranty shorter than some competitors offer at no additional charge.
When weighing the ASD against the Asus or Viewsonic 27" 5K display alternatives, a shopper may need to run that list and decide which things matter, how much and what they're worth. Apple is still selling ASDs and they still get praise.