Before practicing you were worse, and afterwards have improved.
To be clear, it is only one skill in your toolbox
One side project I did in my spare time outside of work got me onto my PhD and has literally saved people's lives. People here probably think that's a waste of time and I should have just lazed about instead.
I think the point is that real-world experience often doesn't translate into Leetcode skills, meaning that you have no choice but to devote time to the otherwise-useless[0] skill of solving Leetcode problems. If making a cool side project, etc. was what helped most software developers get better at interviews, "people here" wouldn't be complaining in the first place.
Sure, you are learning something by solving Leetcode problems, but not anything useful[1] except in the artificial world of software interviews.
[0] This is probably heavily dependent on the specific jobs in question—I'm only speaking from my personal experience.
[1] Same as [0].
Lots of people want a job slightly different to or at a higher level than what they currently do, so they don't get to exercise the skills they will need at work and practice them at home instead.
I don't get why people here are so hostile to people investing their time to try to better themselves and achieve their goals.