Yes, that's right - conventional fretted instruments approximate to the right intonation, and always have done! In practice, the ear gets used to the slight imbalances produced by the "normal" fretting.

If you play, you will almost certainly have noticed that some chords in particular keys might sound slightly out - so much so that you have to adjust tuning slightly so that all chords sound OK. So, you might play something in the key of G, for example, and then make a slight adjustment for playing the next tune in D.

It's rarely bothered me in 50 years of playing, but I must admit I wouldn't mind having a crack at a fan fret instrument.