True but the reason that guitar tabs missing the duration of the notes is not much of a handicap compared to traditional sheet music notation is that the guitar players learning popular music already get the notes' durations from listening to the actual recordings.

This is the same reason that printing out the lyrics for songs don't require notations of durations for each syllable of every word. People singing karaoke or whatever already get the durations by hearing the recordings. (Indeed, lyrics sheets are also missing the pitch of each syllable.)

On the other hand, traditional notation was invented before recordings so musicians often had no idea what the music sounded like unless they correctly decoded the notes durations on the page.