why does everyone have the same size of sigs when some people dont have sigs and some people have very mall sigs and its like pointless having a big blank spot wheres theres no sig

specify and use commas , its hard to read .. people choose the sig size they want, the ones who doesnt want a sig, they have a blank space hope this is what you asked

That doesn't even look like a question, more like rambling.

First of all, if there is no sig specified by the user, there is no sig in the post. (not even the line)
Second. The sig shows just below the post. And the height of the column where the post is, is the same height as the column where the avatar and user info is, which explains the white spaces below the sigs if the message is too short.

Plus you can't have huge sigs

Maximum signature dimensions: 590 pixels wide, 125 pixels high, so most of them are the same size to make max usage

And everything looks all nice and equal like that as well