Yes, its default setup looks like Windows. Yes, 4.0 to 4.2 was the dark days (and the devs openly said that they're considered tech previews, back in the day).
However, when some spends some time with it and tunes it one's liking, it becomes a third hand. Dolphin handles tons of protocols and have features that makes 10+ applications unnecessary. Some of the "effects" are actually usability improvements, which are indispensable when someone starts to use them.
People may not like it, it may not be space efficient as some GNOME themes or macOS, but that thing works, doesn't crash, and improves productivity.
And, you don't change settings every day. I'm opening settings app so rarely that most of the settings either changed or evolved over time. I don't know what's where. I just use it the way I installed and tuned god knows when.
Plus KDE ecosystem has some of the best tools in its class. Did anyone give a good run to KATE and Konsole recently?