The root cause here is that unlike native OS controls, most native web controls are primitive as heck.
So companies that don't want to look like Craigslist end up either using an off-the-shelf UI controls library (not a bad decision, in my opinion), or building their own.
Along with the second option, a new set of disciplines is emerging: the design system designer and engineer. Since companies have grown so accustomed to building their own bespoke design language (instead of using the one the OS ships with), it's doubtful that a well-designed set of modern, native web controls (that ship with browsers) would be able to compete with the notion of "having a bespoke design system".
Also, white-label libraries (like Radix UI) are increasingly appearing that handle all the implementation details and leave the appearance to be defined.
So companies that don't want to look like Craigslist end up either using an off-the-shelf UI controls library (not a bad decision, in my opinion), or building their own.
Along with the second option, a new set of disciplines is emerging: the design system designer and engineer. Since companies have grown so accustomed to building their own bespoke design language (instead of using the one the OS ships with), it's doubtful that a well-designed set of modern, native web controls (that ship with browsers) would be able to compete with the notion of "having a bespoke design system".
Also, white-label libraries (like Radix UI) are increasingly appearing that handle all the implementation details and leave the appearance to be defined.