Ok, so the Instagram biography is meant to describe you, then why is describing yourself in it wrong?
There are 2 reasons for it -
To make it more clear, it's just like the "Sell me this pen" scenario.
If you go and describe all the features of the pen, no one would be interested in actually buying it.
But show them the need for the pen and show how it would benefit them and they'll definitely buy it.
Similarly tell them everything about you and why your content is the best, they would ignore you.
But tell them what problem you will solve in them, how will you solve it and ask them to take a simple action, they will listen to everything you say.