I have been questioning this, there's a lot a people that I know that says that the charts should only chart songs that have a music video, but I don't know, I think that all song that is declared a single should chart, or what do you think?

USUALLY it's like this:

~singles are the songs with music videos.
~singles chart much higher than album tracks.


HOWEVER, there are promo singles and they dont necessarily have music videos.
Also, some album songs chart if the album is selling really well - taylor, gaga.

it's all about the sales really ~ songs with music videos (singles) sell much more than album tracks.

as long as it has good sales

All songs should be eligible to chart, provided they sell enough.

All songs should be eligible to chart. Videos, performances, and single status are all just extra's to help a song chart highly.