Mobile Chat UI – Color of the bubbles

I'm wondering why in most mobile chats the message I write has a color background and white text (example: blue background and white text, like facebook) and the response is on grey background with black text.

The bubble with blue background and white text stand out more than the response which is what the user is going to read.

I leave an example of what I'm talking about.

Screenshot of chat with coloured text and backgrounds