Thanks for your reply. You're right that it's common, but it's still wrong according to the Manual of Style. Links should only be included if they're useful to the user: too many links are distracting. It's not useful to link every possible word when there's no doubt about its meaning. So, to take a cricket example, if you write "He played his first Test match in 1928", it's useful to link "Test match" because people might not know what a Test match is and might want to follow the link to look it up. But it's not useful to link 1928 because everyone knows when 1928 was, so the link doesn't help anyone.

 But you don't have to take my word for it. This is explained in detail in Wikipedia:Make only links relevant to the context and Wikipedia:Manual of Style (links).

 Thanks,