What is the use of blogging?
It's a test kitchen for ideas.
It's a practice court for writing skills.
There are many millions, perhaps hundreds of millions, of blogs in the world. Actively maintained blogs may be significantly less, but probably still number in the millions. Only a handful of these exercise any influence in any domain. Blogging out of a desire for influence (unless one already has influence from another source) is, well, silly. It's certainly not why I would start blogging.