Services provided by third parties - like guest books, or news feeds, or even visitor meters - won't be provided by Blogger, to everybody's liking.
In some cases, Blogger / Google will provide one version of a given service - like Blogger Comments, Blogger Feeds, and Google Analytics - but their versions aren't the most popular in many cases. And some blog owners will develop their own simple applets, like the Cumulus / Google Translation Bar. Bloggers are like any people in any walk of life - they all want something different - better - or new.
With a Classic template, you just had to edit the blog template, using the HTML Editor, to add what you wanted. This frequently brought back the Google Blogger Help forum Customising Templates, and constant questions about how to add a feature and later how to fix a broken template.
Any blog accessory object, provided as a single block of code by a third party service, can be added to your blog as just another page element, to any blog not using a dynamic template. And just like any other page element, you can add and position it on the page, using the dashboard Layout wizard.
- Select "Add a Gadget".
- Do not select "Add your own", and use the "Add by URL" option.
- Paste or type the code into the Content box. Be aware of possible confusion from the "Html" / "Rich Text" gadget label.
- Check for, and remove, gratuitous line breaks from the code.
- Hit "Save Changes" (D'Ohh).
- Reposition the new page element, as necessary.
- Hit "Save".
HTML objects - positionable anywhere on the page, like any Layouts gadget - without editing the template. So versatile, and easy to setup.