Errata can be made to a card for a variety of reasons, including to fix mistakes, to update a card's terminology, or to clarify the behavior of a card so that its rulings are easier to understand (such as Problem-Solving Card Text)
A 2 mana 2/2 creature that can be played in response to a fetchland like Wooded Foothills, a watered down version like Fabled Passage or Terramorphic Expanse, a ramp spell like Three Visits, or another means of cheating cards into play like Kodama of the East Tree in order to ramp out one Plains card from your deck is already good value
I wonder if there's a compilation of them on Youtube or something
This effect may seem purely defensive at first, but you can also use it offensively
Only Aether Channeler and Mumuration make Birds , but thankfully, Murmuration makes a lot of them