It's not nonsense. At least it hasn't been for me. My memory retention shoots into the stratosphere when I write stuff (that I need to remember) down. Something about it being slower and actual effort needing to be expended to commit the information.

Handwriting is my primary notetaking route, but in situations where it isn't (typing is faster after all), I'll scribe what I typed into my reMarkable later. If the note I created was for work and I wrote a note by hand first, I'll type it into a Google Doc later and upload both versions (since they might differ slightly). I learned this as a study hack while I was in school 15+ years ago and it still works flawlessly for retention.

Handwriting everything has held me back sometimes, though. Ironically, insisting on handwriting everything is the reason why I didn't keep a daily journal for a long time. I started journaling in 2012 and stopped as work and life got busier. I picked it back up in 2021 with a mood tracking app to, well, track my mood and reactions to emotions and fairly quickly regretted not having just typed my journal entries.