Is not having a female best friend my red flag in dating?

So I have recently seen in reddit a post, where many commenters pointed out that "a guy not having any female friends is already a red flag" and shouldn't date him". I was so fcckin disgusted and shocked as to how this is possible.

See, I am already an introvert, and with most of the people around in the total of 4 yrs (I am currently a final year btech student) most of my batchmates know me by my name and so do I also know most of them. However, with none of them do I have this so-called friendship.

Note that I am talking about "FRIENDSHIP IN GENERAL", so you can see that I have very few friends even in total, which (for obvious reasons) are males. I can call only them the ACTUAL FRIENDS (which are 2-3 in number I would say) with whom I talk to almost daily and share almost everything, even sharing family related things.

Now, I do believe I am not the only one like this, there would be many as introverted (or even more than) as me. And I also don't feel I have any kind of so-called communication gap with most of the people (I know it cuz I fcckin cracked GS in the brinkest time of Economy and job market). And I believe there would be numerous others like me like that.

So just, tell me, how can I illogically be tagged as "red flag" when I just chose not to have too many friends (and definitely not the female ones)?