I’m “taking one for the team.” 
Seriously, that video is spot on. The 11" is perfect as a tablet and an occasional “laptop replacement.” The 13" is better as a “laptop replacement” and an occasional tablet. I have both the 11" and 13" iPad Pros, a 14" MBP, and, of course, the iPhone 17 Pro Max. My ideal is to have only one device plus my phone.
I estimate that 95+% of my work consists of reading, writing, meetings, and presentations. The other 5% consists of occasionally reviewing a spreadsheet or developing a short slide deck. I do not need, and have little interest in, automation. I genuinely believe I can get by just fine with an iPad Pro.
Initially, my biggest concern was ensuring that I had backups beyond iCloud, which is not really a backup. But I have successfully moved all of my work into the Documents folder. Periodically, I copy that folder to an external SSD and upload it to Google Drive, giving me copies of my work in iCloud, on the SSD, and in Google Drive.
With iPadOS 26 and Apple’s improvements to Apple Intelligence and Siri, the 13" is ideal as a laptop replacement given the nature of my work. The only friction comes when I’m reading and annotating. In those situations, the 13" is heavy as a tablet but workable.
As the video you shared explains, there is “no right size.” Each size is a compromise. I’m finding that the 11" works fine attached to a monitor if I need a large screen, but generally I do not like sitting at a desk. I prefer to sit in a chair or on the couch in my office.
As to my reasons for this experimentation, it will be a little while before I’m in a position to explain myself. What I can say with some confidence is that “I’m not crazy.”
I have a very rational reason for app and hardware experimentation. I’m confident that my app selection is mostly settled. I’m still working through the hardware.