It's mentioned heavily in the article but I want to emphasize... Preview is the easiest way to slice up and merge PDF files.
When applying for mortgages I needed a lot of paperwork and it was so nice being able to point Automator to a folder of pdfs and documents and quickly set up a little workflow that collated everything, then it opened the documents in Preview, I fixed a few minor tweaks, signed the forms, and sent them off. It felt like I had superpowers.
Downloading a bunch of PDFs from my bank/broker into folder and then running an Automator script to combine them into a single PDF is the only satisfying part of collecting information for my tax return.
I had to recently compile some documents for court, they were in several different PDF's and I did not necessarily want all of it. The ability to easily copy specific pages from one document into one large document. Made life so easy.
There are so many small features in Preview that just makes it such an underrated tool
IMO it’s not as good as preview and idk if it supports annotations or does them as well. But it’s a great lightweight pdf and image viewer and “traditional” Desktop app.