THANK YOU so much for saying this. One of the biggest mass-market computing blunders of the past decade is the Microsoft Surface line*; arguably, part of why they've worked so hard on their x86-64-based Surface Pro line, is to help make the original Surface initiative a bad, bad, distant memory.
I think some users here BOTH:
Underestimate the power and flexibility of a full fledged operating system like MacOS (or, yes, Win10); it's silly to assume malice when technical complexity explains it: Excel is on Windows/MacOS because it's MUCH easier to write that kind of complex application on a full, mature, truly deeply-multitasking OS.
Fail to appreciate how nice iOS is; that you think it's worthwhile to port Excel to ARM-on-MacOS is really a compliment to iOS—and you're right, in use case after use case, iOS has found ways to replace the traditional x86-64 platform. iOS 11 just might be the nail in consumer x86-64 computing (with Android after-Oreo trailing behind), ensuring once and for all that full blown desktops and laptops are just for hardcore gamers, serious design professionals, and programmers.
*Notice I didn't say "Pro"; the original "non-Pro" line was ARM