I already EDC that combo in a sleek sling bag, so yes.
You said someone taking around a 13" laptop that was .3lbs heavier than your setup was lugging it around. You're carrying around an iPad+keyboard combination that's .4lbs heavier than a 12" laptop. By your own definition you're the one lugging things around.
When I'm doing some deep work, it matters little whether the screen is 11" or 13", as both are equally inadequate to fit my needs. I need a large display, and that's what I can hook into an iPad and a MBA just the same, where the device itself becomes a Teams/mail sidekick.
That's fine for you - but others may need to carry one device they can do all their work on portably. Not every workflow is your workflow. I need a 14" screen at the very least, and I need to run multiple traditional (non mobile) apps side by side that don't talk to each other, with direct access to the filesystem, where I can arrange them exactly how I want to arrange them. I also need to run software directly on my device rather than remotely because I have to actually plug in equipment.
I need to do this on the go, on location, where I don't have a bigger screen to plug into.
And when I do finally sit down at my desk, I need two external monitors + the laptop monitor in order to do my job most effectively.
The iPad might be perfect for your workflow, but it's not perfect or even viable for many, many people. Your post seems to be implying that laptops are old news and the iPad is enough for 90% or even 100% of people, and that just speaks to a lack of experience and imagination of other people's working lives.
Then at the end of the day, with just an iPad at my side and an external mouse, I can dock it at the office and do proper work, attend conference calls with the excellent 5-mic array, take notes or journal with the Pencil + Paperlike screen cover
I've found the iPad to be quite limiting in this scenario because as soon as you need to take notes, share your screen, do something else while someone is talking (like if they are walking you through something while you do it), etc, your camera turns off.