It's an interesting question. My question back to you is what's the main purpose of your twitter feed?
My main purpose is to inform fans of the most recent LoN episode. I also interact with friends, serial writers, and follow a few websites' updates. That means I keep the number of people I actually follow down because I only want to see stuff I care about, and I don't automatically follow anyone back--especially if they're writers spamming me about their books.
I do a limited amount of Twitter networking (trying to get to know people I'd otherwise never meet), but not a lot. I might do things differently if that were the main point of the feed. Not too differently though--I still wouldn't follow everybody. I'd just include a higher proportion of people I want to meet in my feed.
In theory I may be missing out on meeting wonderful people that way, but my experience argues that I'm actually missing out on posts I have no interest in. Thus, I'm choosy about who I follow.
To actually answer your question though, I don't think it means much--at least if they're collecting numbers without a real purpose behind it.
I have had useful and interesting conversations with people on Twitter, but it's more for chatting and networking than building readership for me. It does however make it easier for some people to follow the serial, and thus I've set it up so that my updates automatically go into my Twitter feed.
Occasionally people retweet my updates, and that has the potential to bring readers in, but that's not why I'm doing the feed. It's a nice side effect though.