Why are Trolls not blocked

Thats it. Why are the obvious repeat trolls not blocked from using this site by the mods?
You may just as well ask, why are all speakers imperfect? :)

Whatever are you referring to?
A lot of people get accused of trolling at some point. The internet would be a ghost town if everyone did that.
@jond  & @dwmaggie.....because the listeners aren't particularly perfect, either....;)
Due to whatever another may be claiming, or not...

The problem with an 'open forum', one could point out...is that it's Open.

One can agree...or not.

Ain't it grand! *VBS*