@ivanomonti ...Well.. I think that the problem is not the webview... but the way of using...
Why? ... because if webview had all the tech of a browser... then webview had to be a hacker tool... why ? imagine creating a loop trying to login that will a bruteforce system... that's why is not doing for that purpose...
But for login to some accounts needed to use new technology... like SOAP/ API giving you the service wanna login... sometimes give a token too.. and most times communicate using json...
Technology moves forward so all services... or the most need to use their API to connect to them...
The only way to use webview to login somewhere is if the webpage gonna connect using simple GET tech... and as i know the most of webmasters not using it anymore...
The bad in all these... is to know everytime how will connect to every service and how will get the info... so you must learn everytime the API needed :-(
ps: There is also Selenium that is something like browser... and use like use by a Robot... but also for me this is not the right way "today" to connect somewhere...