If scriptures say it is better to stay celibate, why are we also told to be fruitful?
The only scripture I find that might say it is better to be celibate is in 1 Corinthians 7. Paul there, though, says that it might be better “for the present distress.” (1 Corinthians 7:26) As he makes clear in the whole chapter, there is nothing wrong with being married. For some it is preferable. During extreme persecution, however, having a family might put added pressure on one to give up his faith to save his family.
That Paul is not advocating celibacy as preferable in all circumstances is clear from his other writings. Although he told the Corinthians it might be better not to marry, he told Timothy that those who depart from the faith will forbid people to marry (1 Timothy 4:1-3) So he clearly was not forbidding marriage. Throughout time God has commanded man to be fruitful. He has not changed that command.