> Every company use different technology and different way to do things
To a small extent, but mostly untrue. If you are an expert UI programmer, you should be able to move between disparate UI technologies relatively easily.
> With a standardize test
People aren't upset with the standardized test part. They are upset it (frequently) tests things that are not relevant. Hard things at that. There are an extensive number of practical, language / framework agnostic questions you can ask about UI or back-end programming that will easily tease out quality candidates. Instead they ask you merge sort. Hence people complain.
To some extent but the topic is still relevant, leetcode topics are algorithm, data structure, system design, etc.
Again whatever interview scheme you devise nothing is perfect. To me at least the pros outweigh the cons.
>so even someone who _doesn't_ have the requisite experience could learn it?
I consider it a plus. Every company use different technology and different way to do things. Not to mention it keep changing all the time. With a standardize test, even though I don't have the experience with the technology they use, i can still have have a shot.