Style guides have three very useful functions, the third and least important of which is to help you write with style. Strunk's has rules aplenty, and while many of them are now somewhat dated or country specific, such as the Oxford comma and placing punctuation outside parentheses rather than within, the book is an interesting and readable guide to some of those style 'rules'.
The two other functions of style guides are much more important though. Firstly, you get to be smug towards people who don't understand that there are 'rules'. People who were unlucky enough to have a 'comprehensive' education or who just don't think it's very important. This is a lot of fun.
Secondly, and even more fun than the first function, is the opportunity to be smug over people who think that the 'rules' must be slavishly applied without thought to changes or differences in style or even a personal style. Again, those Oxford comma obsessives are great guys...
Who knew grammar was going to be so much fun!