A huge downside of writing this down on paper is team collaboration. Imagine that instead this is kept in a tool like Notion which the entire team can access. At first this feels incredibly uncomfortable - your notes are there for everyone to see. However it’s a massive force multiplier because often the work is picked up by someone else later on, and instead of asking you they can self-serve. It’s pretty common that…
All lab notebooks are company property. You don't keep them locked away in your desk or take them with you when you leave. Any current or future employee with the right clearances should be able to serve themselves to the entire archive. No need to ask the original author.
Searchability is by far the most significant advantage of electronic documents, but you can get pretty far with paper notebooks if you keep a decent table of contents. Even better if you regularly scan, OCR, and upload your pages to the archive. IMO the inconvenience of scanning is greatly outweighed by the paper notebook's guarantee of immutability. Tools like Notion make it too easy to erase information, either accidentally or not.