- I wanted to create a grid of img like elements(something a bit more complex where you have some small buttons on each image), I hit the issue that the browser would take like 2 seconds to load 1000 elements, in a decent GUI toolit this is not a problem, as an example in Flex4 I can have a list with 1000 elements, if only 10 elements are visible then the toolkit creates say 16 GUI elements, as you scroll the elements that get out of view are recycled , in Web you either create all 1000 GUI elements(that each element is maybe formed with a giant div soup) or you use a infinte scrolling like pattern, check Youtube as an example, go to a specific channel video list, you see only 2- 3 rows of videos, then you scroll and wait for next few rows, scroll and wait again, scroll and wait again ...tldr web GUI performance is really bad
- native components are limited, you can't css properly and consistently a numeric input(you can't css the colors of arrows to fit your styles) , you can't have a dropdown that contains icons or some more complex thing like a "Font Families dropdown" , you can't customize the dropdown scrollbar colors so you are forced (is not my fault that desingers want shit to match in theme and not have white crap on a dark theme) to find or create custom components, so you get to import JS libraries and most of the time this components are broken, Ex check the youtube search dropdown, it happened a few time for me to get the dropdown in the search to get stuck open, only way to fix it is to reload the page, Google devs can't properly implement a correct dropdown widget. In PayPal their custom input widget to enter money does not support the "Del" key . In a decent widget toolkit you extend the existing widget, you get all the existing functionality and you add your custom features on top in Web you start with DIVs and CSS do a mediocre job and then fix the issues that get reported if you have the time.
All this issues are solved in Qt, Flex or WPF, the components are performant, you can customize without losing basic features, you don't have to research shit like "what library should I use Monday to implement the numeric spinner input" .