No! It's not! Not in 2018! You only think it's impressive because you're used to UI's being total fucking shit! That's why it's an indictment of the software industry!

I'm not saying it's not hard: it is hard. Programming is hard. Making sure you're not occupying the UI thread for more than 16 milliseconds per frame is sometimes a challenge. You have to use all sorts of scary stuff like "concurrency" and "threads" and "GPUs". But it's 2018: non-laggy UI's should be the baseline everywhere, for everything.