You'd ask me - why web design? You're not a programmer. You don't know how CSS or HTML works. Well, web design isn't just about the nitty gritty coding that happens behind. Remember that there are WYSIWG website builders around, hence marketers need at least some basic understanding of site structure and UI/UX.
And this is as simple as using data analytics tools like Google Analytics. Part of digital marketing is tracking every click, viewing page views, monitoring user location, et al. There's just so much data to analyse.
With more powerful software and better AI, mundane tasks are starting to become automated. Shrewd people know this - the more tools they use to simplify tasks such as creating chatbots to automatically respond to general user queries, the faster the job gets done.
Chime in your thoughts if you have any other critical marketing skills every marketer needs this year!