I like writing by hand, but I don’t agree with the logic that it’s good because it recruits more areas of the brain. The less effective the medium is, the more of the brain it will recruit; chiseling on a stone tablet is probably a more complex task and it probably gives a more broad stimulus to the brain, but it does not mean it’s such a good idea. I would personally prefer to use a text editor for effective writing and then crochet for fine motor skill.
Right, it's a false signal. It doesn't mean that more things are retained.
I think what happens in these types of threads is that the people who like handwritten notes, perhaps even obsessively so, all pour in. But that population of handwriting fans isn't necessarily representative of the population overall.