There's a lot of workflows that are hampered or impaired on an iPad beyond programming. Yeah, with kludges you can kinda get most or even all of it done but usually in a less efficient manner. Missing or limited programs, limitations on using peripherals, and moving data/files between apps drags things down.
I have an iPad Pro 12.9. Once in a while I try to get things done on iPad only. No, no programming, other stuff. Every single time, I end up going back to my real computer and regretting wasting time figuring out how to make things work.
I think parent's point is these people probably still kept a laptop on the side, even if that's not their primary device.
And it's totally fine, but we could be at a point where there was absolutely no need to keep a laptop "just in case" or for the rare occasions it's needed.
I like the Connected podcast's take on it, where at some point two of the three hosts where primarily on iPad, but keeping their recording setup on the mac and a few other task where they needed another computer as a bridge for random reasons.
There are millions more who use it as a content creation tool, despite HN users' insistence of that impossibility.
One of my favorite youtubers (1M subscribers) produces his video content on and runs his channel from an iPad.