If you do this and, say, tweet a blog post, you're going to get a high proportion of your followers clicking on it. You might only need a couple of hundred of them to get several extra clicks every time you tweet a post. Now, if you have thousands of followers who are just following you because you follow back, then very few will click on your link.
Also, if you intend to use Twitter to draw some links to your blog then a quality following is important. It's always much more likely that people will link to you if they respect your opinion, and feel they know you.
Take one tweep who has ten thousand followers. He doesn't really care what they're into as long as they follow him. He never interacts with any of them. Sure, if he keeps tweeting his blog posts he'll eventually get the odd click every now and then. But getting a link from one of them is even less likely.
Consider another tweep who's made a point of following knowledgeable people who share his specific interests, many of whom are bloggers. He tweets consistently interesting content about those subjects. He's only got 80 followers but they're pretty much all bloggers in his niche and he interacts with them a lot. Not only will he get a much higher proportion of views on blog posts he shares, but the odds of some of those viewers (bloggers themselves) linking to them go way up.
The best thing about building a quality following rather than one based on quantity is that it actually takes less time and effort. You can start interacting from day one, and get some traffic pretty soon after that. However, if you want the numbers more than anything you'll be spending hours and hours following others in the hope that they'll follow you back, rather than tweeting and engaging thoughtfully.
The other benefit of focusing on quality is that you will slowly build up a sizable number of followers anyway. But they will be knowledgeable and engaged, drawn to you because you tweet interesting stuff and interact with others.