What is the reasoning behind the Unsealed Spellbook change?

I don't get why they are making the changes that they are. From how I understand it:

-Can swap spells anytime out of combat -Once you swap a spell out, you cannot swap back to it until you do 3 more swaps -The swaps get slightly faster the more you do them

For me, normally I use spellbook on supports by starting with an early game spell (Ignite, Barrier), usually swapping to Tele during mid game, and then exhaust or cleanse late.

I don't really see the reasoning in locking out spells with more arbitrary swaps, and I don't see why switching back and forth between ignite and teleport is being changed. I definitely do see an issue with Teleport being available at any given point in the game regardless of what you took in loadout, where someone can quickly duck into a bush and change to tele immediately.

Why was this change made?