>> Modern web apps are less about being performant and minimal, and more about dealing with the complexities of large software teams
If that's true, then the app will likely have what I call a "programmer's interface" (which is especially common in most enterprise web apps I encounter). Those apps might be solid from a code perspective, but don't tend to be very user friendly.
I tend to think that modern web apps are more about dealing with the complexities of balancing functionality with ease of use to the end user while still dealing with the complexities of large product teams, which include but are not limited to designers, UX experts and developers.
I agree that following browser default behavior is more intuitive in general. I'm not a fan of scroll jacking.
I'd say apps skew towards mouse-heavy because controls are on-screen and therefore discoverable. It takes a good deal of product-market fit before you can count on your users knowing/caring enough about your app to remember keyboard shortcuts.
Most apps are grown by adding users, so optimizing for the new user is more important to the business until a certain level of maturity and market saturation is reached.
Applications with a dedicated professional user base can go deeper into power-user territory sooner since they can charge more per user, and new users expect there to be a learning curve.
If that's true, then the app will likely have what I call a "programmer's interface" (which is especially common in most enterprise web apps I encounter). Those apps might be solid from a code perspective, but don't tend to be very user friendly.
I tend to think that modern web apps are more about dealing with the complexities of balancing functionality with ease of use to the end user while still dealing with the complexities of large product teams, which include but are not limited to designers, UX experts and developers.