There are several great monolingual dictionaries one can use instantly, but not the OALD (http://oald8.oxfordlearnersdictionaries.com). Why is so? In my opinion, it’s one of the best up-to-date English dictionaries.
Because it isn’t free?
Ok, let’s put it this way. I can use Cambridge, Macmillan (an so on) online dictionaries creating lingQs, but not the Oxford… You mean, adding link to Cambridge is free, but not the same for Oxford? I don’t think so, especially if you bare in mind that everyone can add Oxford Search Box to his personal site/blog for free.