Absolutely not, for some use cases it just makes sense to use a MBP - motion graphics, heavy video editing, AutoCAD, 3D Models etc. But when this isn't required and you just need something to type up a blog on the go before you update your website later in the evening it's fantastic.
That's not to mention those who need it for portability. Myself in schools, having an iPad compared to a £3K MBP is much easier for anxiety when children start touching your screen to see xyz. It's easy to just walk into a meeting and bring up some stats when you're already connected to 4G, no WiFi business, just straight in there. No need to deal with finding a certain window or application, everything is just there.
I think if you're really portable, it makes sense to have an iPad. I don't just mean from desk to desk, I mean actually moving around, think about in a classroom, or on a construction site, in hospitals etc. You just want the screen there, nothing to prop the laptop on, easy to hold in one hand, and you only need the keyboard when required.
For me, it's great having the power of both, I thought I could take my MBP around, but that just remains docked. I wished I bought an iMac instead. Once the new ARM ones are released, I'll hand this MBP to my sister or sth.
! Her school started iPads in the classroom in kindergarten and then grades 3 to 5 everybody gets one to take home. It’sa public school, albeit a very good one.
