I have a complete different experience also as contributor in the core since various years and in other WP official projects (and also as co-maintainer of VVV).
WP contributors exists, but commiters that can review code are very few compared to the rest of people. I think that the discussion needs to exclude Gutenberg/fse as the people working on are completely different from the rest.
As today is normal that a patch that fix a bug or a PHP warning/error takes years to be reviewed and maybe get in the next release.

During wordcamp or slack chat I got various time people saying "you need to ping the committer/maintainer privately". This means that they cannot check everything, so they listen what it is under their eyes.
I know that there are committers that check only tickets by last change, so if a ticket with something useful is not followed in this timeframe when they check manually well it will be forgotten.

The only reasons I am getting my patches approved since I started is that I am pinging some committers I know with a list of tickets and maybe of that 1-2 get reviewed and finally merged.

I am the only one that checks the ticket proposed at every release from the make post and how many of them get addressed in the next major at the end?
I have now less of 20 patches waiting for a review or a comment, and the most old waiting is dated 2015.

The onboarding of contributors and so on is not simple, so is clear that just committers that do that as job only can handle everything.