As a few other people have mentioned, there are reasons as to why you wouldn't want to have to click an article and scroll all the way to the bottom to vote. It's convenient having it on that page.
The whole point of Steemit is to engage. It's a social network. We're supposed to be getting to know one another, sharing information, and forming relationships, not trying to make a fast buck clicking vote buttons on our feed lists.
Almost every social network lets you interact with the posts before you view the full content of a post. Why should steemit be any different?
A lot of people complain that a problem here on Steemit is that many curation votes happen without the voter ever reading the content they're voting on.
I think the reason they complain is because of bots. But the thing is, bots don't visit steemit.com, they vote directly on the blockchain. That means removing the button from that page would do nothing to help the problem itself, and might just annoy someone who has a valid reason for that button to exist.
Even though I may not agree, I appreciate and encourage the conversation!
Yeah, there is also this whole thing about "Decentralized Curation Guilds", like the operator thing on Streemian. While it is cool, that my voting power is being spent on good things (I hope), when I am away from internet, it also means that those votes don't have my eyes behind them. I am somewhat torn by the implications, but I try to go and check out the stuff that my votes were cast for.