Earlier quoted context omitted.
"wxwidgets has a very antiquated feeling to the API" This should not be relevant in any professional technical discussion. Last time I looked there was not an overflowing oversupply of cross platform UI frameworks. "it didn't ship high DPI support " This, on the otherhand, might be a critical deficit.
At least on Windows, there's a new UI API every 7 years. MFC, Winforms, WPF... Maybe "wxwidgets has a very antiquated feeling to the API" really means that platform-neutral concepts do not encapsulate well when keeping the UI truly native?
It's still useful to have a single UI library in your code that you can tell to make a text box or open a menu or draw some graphics and have it translate into the correct API calls on each platform under the hood. For all the much-touted rearrangements of UIs, particularly in recent versions of Windows, the reality is that most of the familiar GUI controls haven't really changed that much in decades.
I think the biggest difficulty for any attempt at a cross-platform GUI framework today is probably making sure it does properly handle the widgets or behaviours that really are different or unique on each platform. More generally, if you're building for multiple platforms you also have to deal with all the installation and updating and sandboxing and so on that tends to be completely different from one OS to another, and often the GUI libraries and UI integration is a big part of that too.