Because pagan/neopagan is basically anything NOT Christain or the other triad in the abrahamic religions. Plus, so many people have misconceptions about Hinduism (and/or Kali in general) so it helps give information about them. I’m saying this as someone who identifies as Pagan, myself.
“anything that isn’t Abrahamic is pagan” false, Hinduism is a Dharmic religion along with Buddhism, Jainism and Sikhism. These two groups (Abrahamic and Dharmic) are also joined by Taoic religions (which include Confucianism).
the term pagan being applied to non-Christian/Abrahamic religions is archaic and disrespectful – the term pagan is used “presuming a belief in false gods”
Organized Hinduism/vedic-puranic Hinduism is Dharmic. Some aspects are derived from various Indian indigenous belief systems. Those are the terms you should be using.
Repeat after me: label non pagan polytheistic beliefes as pagan is Disprectful.