Up until the early 2000s I used to compile my own kernel, carefully selecting only the options that I needed.
Then I realised that I wasn’t saving memory, because almost everything was a module anyway.
Is there any actual benefit to using a custom kernel on consumer hardware that’s supported by the stock kernels?
For consumer hardware supported by stock kernels? No advantage at all. At most you may want to switch kernels, but most distros have a handy tool for that.
The only time I’ve compiled my own kernel in the last 15 years has been for work on very specialized embedded systems.