Widgets generally accomplish one or more of the following things:
1. improve the functionality of a site by providing reader accessibility to content that is not located on the front page;
2. act as leaders for e-commerce or other transactions;
3. promote and lead traffic to the site serving the widget;
4. redirect readers to high quality sources of relevant information found in authoritative blogs in the same niche.
1. Follower widgets slow page loading time as each little avatar must be loaded from the site providing it before the whole page is displayed. At least half of all internet users are currently using dial up connections. What that means to us is that half of our visitors are downloading the pages at about 3-4 kilobytes per second. And it’s estimated that if a page has not loaded with within 8-10 seconds we can stand to lose one third of our visitors. Also note that Page loading time is now a Google Page Ranking factor.
2. Follower widgets and all other sidebar clutter AKA "tat" distract readers’ attention by drawing the eyes and mind away from the content in our posts to the sidebar.
3. Follower widgets do not provide access to additional resources to the reader thereby enhancing their reading experience. They compete for attention with navigational links to deeper content in our blogs found in our in our sidebars.
3. Follower widgets spoil the design and give the blog an amateurish appearance. I have yet to see a follower widget filled with teeny tiny little avatars that enhanced any blog design. I also note that no blogging pros use them at all.
4. Follower widgets serve no useful purpose at all other than the narcissistic one that comes from displaying a larger army of "followers" than the next blogger has.
5. Follower widgets leak link juice.
I can't think of any and that's the truth.