Here’s my take….
1. TAB is important.
2. Teaching students to be literate musicians (who can read sheet music on a staff) is important.
3. Teaching students to be able to continue to play once they leave your class is important.
So with those three things in mind…YES…I believe we must teach TAB, but at the correct time. I think students need to have a firm foundation in notation FIRST. Once that is established, yes bring out the tab. It really will be important for them to know once they have left your classroom (especially if they are only with you for a short time like my students are).
HOW TO INTRODUCE IT:
I’ve found that telling students that TAB is just a map of your guitar turned sideways works well.
I always use Cream’s “Sunshine of Your Love” to introduce it. Great lick that you can walk them through just a few notes at a time. You can totally tell if they’re picking it up by when the riff changes. The change is shifting what you’ve already learned up a set of strings. If they understand tab, they’ll get it without a problem, if not….better go back and explain some more.