Using a chat application or scrolling through a feed is not hard. Users can easily learn a new UX if the product really provides value. Yes, having better UX is good for many reasons, but people have always learned to go around bad UX in order to achieve their goals. Facebook has a shitty UX, I never find what I'm looking for, spammed with ads, fake news, slow loading times, bugged notifications, yet it's still one of the most popular sites on the planet. Their ad manager is a joke when it comes to UX and bugs, yet people still spend billions on advertising on Facebook.
And so, it blows my mind how Instagram and WhatsApp have continued to get their UX right despite adding so many features over the years. This is super hard considering more than half the world, not all of whom are technology savvy, use WhatsApp and Instagram on daily basis with flawless understanding. I mean, sure, they might struggle a bit, but it isn't anywhere close to frustrating them unlike other popular software. Not to mention how frictionless, smooth their entire UX is.
I guess, design focused on content consumption is easier (Email/IM) than content creation (Microsoft Office)? Or, may be, the value of popular software is such, that people put up with it, anyway, and learn to live with it despite the UX?