Is the "either all GTK or all Qt" mentality still relevant today?

I ask this because I remember people arguing about it all the time.

However, nowadays there is a lot of disk space usually, so having two GUI frameworks installed won't really make a big difference - except for those who like to have very few packages installed.

There is also people who use GTK apps when using GTK DEs and Qt apps when using Qt DEs. I get it, but wouldn't it be better to always run the better software, regardless of GUI framework?

I use quite a few GTK apps in KDE Plasma. It used to look and feel very off, but recently I can't even notice the difference most of the time. It all integrates so well.

When programming, I prefer Qt, but when I'm using software I don't really care.

So I guess I have a more couple of questions

• If you like having very few packages installed, assuming you have plenty of free disk space, why?

• Is running Qt apps in GTK-based DEs as seamless as running GTK apps in Qt-based DEs?