I have a head but no brain. I have a tail but no body. People come to me when indecisive. I jump at the opportunity to help you make a choice.

what is full of holes and still holds water?

Skip to the end of a text to find me I’m not necessary, you need not remind me. Some walk without me, not off much worse. Because I got angry and threatened to burst.

I started as a fairytale creature then became part of the everyday internet lifestyle.

To make a riddle that rhymes, that's the trick; with a formatted verse that's quite slick, you rhyme stanzas in pairs, and when caught unawares, back to first, that's this poem's whole schtick.