Answer by taking a quote from the following article:

Charles Taze Russell was born to Scottish-Irish parents, immigrant Joseph Lytel Russell  (d. December 17, 1897) and Ann Eliza Birney (d. January 25, 1861), on February 16, 1852 in Allegheny, Pennsylvania. Russell was the second of five children, of whom two survived into adulthood. His mother died when he was 9 years old. The Russells lived for a time in Philadelphia before moving to Pittsburgh, where they became members of the Presbyterian Church.

With the formation of the Watch Tower Society, Russell intensified his ministry. His Bible study group had grown to hundreds of local members, with followers throughout New England, the Virginias, Ohio, and elsewhere. They annually re-elected him "Pastor", and commonly referred to him as "Pastor Russell". Congregations that eventually formed in other nations also followed this tradition.  In 1881, Russell published his first work to gain wide distribution: Food for Thinking Christians. The 162-page "pamphlet" was published using donated funds amounting to approximately $40,000 (current value $1,014,345). It had a circulation of nearly 1.5 million copies over a period of four months distributed throughout the United States, Canada and Great Britain by various channels. During the same year he published Tabernacle and its Teachings which was quickly expanded and reissued as Tabernacle Shadows of the "Better Sacrifices", outlining his interpretation of the various animal sacrifices and tabernacle ceremonies instituted by Moses. Russell claimed that the distribution of these works and other tracts by the Watch Tower Society during 1881 exceeded by eight times that of the American Tract Society for the year 1880.  In 1903, newspapers began publishing his written sermons. These newspaper sermons were syndicated worldwide in as many as 4,000 newspapers, eventually reaching an estimated readership of some 15 million in the United States and Canada.  In 1910 the secular journal Overland Monthly calculated that by 1909, Russell's writings had become the most widely distributed, privately produced English-language works in the United States. It said that the entire corpus of his works were the third most circulated on earth, after the Bible and the Chinese Almanac. In 1912 The Continent, a Presbyterian journal, stated that in North America Russell's writings had achieved a greater circulation "than the combined circulation of the writings of all the priests and preachers in North America."  Russell also had many critics, and he was frequently described as a heretic in this period.

Why did they do that?
These newspaper sermons were syndicated worldwide in as many as 4,000 newspapers,