There are many dozens of top level domains which you would want to look through, perhaps more than you realize. To look through all of them at the same time not only would require multiple searches (one for each domain extension). Not to mention wasted time gathering results that aren't necessarily wanted (how many times have you wanted to search for blah.nf?). If you want to look through all 250+ top level domains in real time, then be my guest. I wouldn't advise it though.