Leetcode is only a useful problem to ask if the candidate has not encountered that problem before and has not practiced leetcode. Otherwise it is exactly as good a signal as knowing some arbitrary framework or database.
"Grind" just means "memorize a bunch of stuff for later regurgitation", which is the same thing as is demonstrated by memorizing the API for some arbitrary database or javascript framework.
Willingness to "grind" is a positive signal for people hiring developers in the same way that low critical thinking skills is a positive signal for people hiring law enforcement officers, and results in a team of similar quality.
Leetcode is a standardized test that shows your ability to write code, grind and pattern match in a very complicated space. It is not possible to memorize solutions to all problems. There are way too many problems in this space. All the people complaining about leetcode are a prime example of this. It takes a lot of time and background knowledge to learn all the algorithms, data-structures, and problem-solving patterns... to get good to the level where you can ace FAANG and trading interviews with a high probability. It's a more useful metric than memorizing specific APIs which is not standardized, has basically no/simple pattern matching, and does not really test coding skills. There are also too many frameworks, and this just doesn't stand the test of time. People would need to constantly re-learn frameworks for interviews.
Most companies have been using leetcode and system design for dozens of years for a reason. It's not changing anytime soon.
Also, leetcode can be really fun :) if you remind yourself to be truly curious about the problem.
Leetcode is only a useful problem to ask if the candidate has not encountered that problem before and has not practiced leetcode. Otherwise it is exactly as good a signal as knowing some arbitrary framework or database.