Yes and no
Isn't it possible for the webmaster of this site to somehow identify the poster you mention and/or others that disrupt the page frequently, through their machine's ID, or some other type of electronic identification, and then sort of "lock them out" of this site?
Just wondering.
Not really, though your question is far from silly and has come up before. There is some kind of draconian means of preventing a specific ISP (your computers signature) from using a website but it can take out civillians in the same area.
Even given that you can do that though, how do you stop that individual using a public access terminal, or setting up a different ISP with the same computer? This is what Doug Grant, a notorious kook who ruined the rec.gambling.blackjack newsgroup, did when numerous complaints were issued to his service provider(s). That route just does not work unfortunately.