I still get surprises like starting to learn Google Cloud Functions and realizing that up until July of this year they only supported Python 2. I have no idea

I still get surprises like starting to learn Google Cloud Functions and realizing that up until July of this year they only supported Python 2. I have no idea why would a project of this caliber would start by using Python 2 instead of Python 3. Edit: When I started reading about GCF, all docs said I could only use Python 2. Later I found that they seem to be on the way to change this. But still, I was very surprised that Python 2 was even an option to begin with.