The worlds of investing and business have changed, making it tougher to buy good companies and giving rise to huge businesses that are based on ideas, not manufacturing plants, Warren Buffett and Charlie Munger said Saturday.Munger, who is vice chairman of Berkshire, said, “The general field of buying whole companies has gotten more competitive,” making it difficult for Berkshire to find affordable businesses to add to its dozens of operating companies. Berkshire’s future growth will be “less glorious than in the past. We keep saying that, and now we’re proving it,” he said. Berkshire’s growth averaged 21 percent a year for its first 42 years under Buffett but 8.7 percent in the decade since.Omaha World-Herald is owned by Berkshire Hathaway Inc.