HTML : Why don't document.getElementsBy__ methods return an HTMLCollection?

To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

As promised, I'm going to share a hidden feature with you.
This is a YouTube's feature which works on Desktop.
First, Make sure this video is playing.
Next, enter the letters 'awesome' on your keyboard.
Your YouTube progress bar will transform into a flashing rainbow.

Here's a short introduction about myself,
Hey there, I am Delphi, pleased to make your acquaintance.
I am capable of providing answers to your questions.
If you need more specific answers, please reach out to me through comments or chat.
If you have an answer, or any insights to the answer, please comment below.
A 'heart' from me will be given as a sign of appreciation for your answer.