Congratulations, and welcome to Mage Wars! It remains my favourite board game after nearly six months now, which is a personal lifetime record for me. ; )
No, it is most definitely *not* correct that a spellbook without at least two teleports will not be able to compete. Teleport isn't good enough by itself to make that claim valid. However. Not including two teleports is (almost) always a sub-optimal decision, and many players argue that not including three is sub-optimal. (I'm not one of the three minimum crowd though.)
Let me try an analogy: if you play a (Straywood) Beastmaster, you almost always want a lot of animals in your book. Since you're putting a lot of animals in your book, you are almost always going to want to include a Ring of Beasts. Will you automatically lose most games if you don't include that Ring? No, of course not. But the ring is so good in that combination, that you need to have a very good reason *not* to include it in your spellbook.
Teleport is like that, but with every spellbook; if you don't include at least two, you need to have a good reason not to. Here are two good reasons for you to use: 1) I don't have enough copies of the spell to use, and I don't like constantly switching out cards from other books. 2) My local meta is different from most other ones, in that they don't play enough cards that would make Teleport truly useful enough to justify the 8-spellbook-point cost (for everyone but Wizard) of including two of them.
Go ahead and create books with only one (or even 0!) Teleport, it's not going to break your game. If you ever *can* though, try to include at least two. Teleport really is useful enough to justify that, in most books.