Yes You can, the "has" just adds a time component. We're looking at the difference between past participle form (I forgot the name of the tense..maybe past perfect) and simple past. In simple past ("he bought a house") time is irrelevant. He bought a house, completed action. With the past participle form ("He has bought a house") it indicates a time component... so you can leave the specific time unsaid, or add "he has bought a house recently/finally"... it can also be indicative of the duration of the time of the buy "he has bought the house after plenty of haggling over the price"...

But, to be more accurate, Michael Jackson didn't "buy the house", he "bought the farm" :P