Original: As the traditional view of billiards as a refined and noble pastime did not blend well with the low-class connotations of gambling, the billiards industry began to distance itself from the term pool beginning in the late 19th century.
Simplified: The traditional view of billiards as a refined and noble pastime did not blend well with the low-class connotations of gambling. Beccause of this, the billiards industry's attempts to distance itself from the term "pool" beginning in the late 19th century.